Ukrainian President Petro Poroshenko gestures while speaking to the media at a polling station, during the second round of presidential elections in Kiev, Ukraine, Sunday, April 21, 2019. Top issues in the election have been corruption, the economy and how to end the conflict with Russia-backed rebels in eastern Ukraine. (AP Photo/Efrem Lukatsky)

Ukrainian President Petro Poroshenko gestures while speaking to the media as her wife Maryna stands next to him, at a polling station, during the second round of presidential elections in Kiev, Ukraine, Sunday, April 21, 2019. Top issues in the election have been corruption, the economy and how to end the conflict with Russia-backed rebels in eastern Ukraine. (AP Photo/Efrem Lukatsky)

Ukrainian President Petro Poroshenko gestures while speaking to the media as his wife Maryna stands next to him, at a polling station, during the second round of presidential elections in Kiev, Ukraine, Sunday, April 21, 2019. Top issues in the election have been corruption, the economy and how to end the conflict with Russia-backed rebels in eastern Ukraine. (AP Photo/Efrem Lukatsky)

Ukrainian President and presidential candidate Petro Poroshenko and his wife Maryna visit a polling station during the second round of Ukraine's presidential election in Kiev on April 21, 2019. (Photo by Sergei GAPON / AFP)

Ukrainian President Petro Poroshenko holds his ballot paper as he leave a polling booth to cast at a polling station during the second round of Ukraine's presidential election in Kiev on April 21, 2019. (Photo by Sergei SUPINSKY / AFP)

Ukrainian President Petro Poroshenko (L) and his wife Maryna Poroshenko hold their ballot papers to cast into a ballot box at a polling station during the second round of Ukraine's presidential election in Kiev on April 21, 2019. (Photo by Sergei SUPINSKY / AFP)

KIEV, UKRAINE - APRIL 21: Ukrainian President and presidential candidate Petro Poroshenko casts his vote at a polling station during the second round of Ukraine's presidential election, in Kiev, Ukraine on April 21, 2019. Vladimir Shtanko / Anadolu Agency/ABACAPRESS.COM

KIEV, UKRAINE - APRIL 21: Ukrainian President and presidential candidate Petro Poroshenko arrives at a polling station to cast his vote during the second round of Ukraine's presidential election, in Kiev, Ukraine on April 21, 2019. Vladimir Shtanko / Anadolu Agency/ABACAPRESS.COM

Ukrainian President Petro Poroshenko gestures while speaking to the media as her wife Maryna stands next to him, at a polling station, during the second round of presidential elections in Kiev, Ukraine, Sunday, April 21, 2019. Top issues in the election have been corruption, the economy and how to end the conflict with Russia-backed rebels in eastern Ukraine. (AP Photo/Efrem Lukatsky)

Ukrainian comedian and presidential candidate Volodymyr Zelenskiy, arrives at a polling station, during the second round of presidential elections in Kiev, Ukraine, Sunday, April 21, 2019. Top issues in the election have been corruption, the economy and how to end the conflict with Russia-backed rebels in eastern Ukraine. (AP Photo/Efrem Lukatsky)

Ukrainian President Petro Poroshenko leaves a booth at a polling station, during the second round of presidential elections in Kiev, Ukraine, Sunday, April 21, 2019. Top issues in the election have been corruption, the economy and how to end the conflict with Russia-backed rebels in eastern Ukraine. (AP Photo/Efrem Lukatsky)

Ukrainian President Petro Poroshenko helps his wife Maryna to leave a booth at a polling station, during the second round of presidential elections in Kiev, Ukraine, Sunday, April 21, 2019. Top issues in the election have been corruption, the economy and how to end the conflict with Russia-backed rebels in eastern Ukraine. (AP Photo/Efrem Lukatsky)

Ukrainian President Petro Poroshenko and his wife Maryna cast their ballots as their grandson Petro, looks at the ballot at a polling station, during the second round of presidential elections in Kiev, Ukraine, Sunday, April 21, 2019. Top issues in the election have been corruption, the economy and how to end the conflict with Russia-backed rebels in eastern Ukraine. (AP Photo/Efrem Lukatsky)

Ukrainian President Petro Poroshenko gestures while speaking to the media at a polling station, during the second round of presidential elections in Kiev, Ukraine, Sunday, April 21, 2019. Top issues in the election have been corruption, the economy and how to end the conflict with Russia-backed rebels in eastern Ukraine. (AP Photo/Efrem Lukatsky)

Ukrainian President Petro Poroshenko speaks to the media as his grandson Petro looks at them, at a polling station during the second round of presidential elections in Kiev, Ukraine, Sunday, April 21, 2019. Top issues in the election have been corruption, the economy and how to end the conflict with Russia-backed rebels in eastern Ukraine. (AP Photo/Efrem Lukatsky)

Ukrainian President Petro Poroshenko and his wife Maryna cross themselves during Orthodox Palm Sunday mass in the St. Michael's Monastery in Kiev, Ukraine, Sunday, April 21, 2019. Top issues in the election have been corruption, the economy and how to end the conflict with Russia-backed rebels in eastern Ukraine. (Mykola Lazarenko, Ukrainian Presidential Press Service/Pool Photo via AP)

Ukrainian President and presidential candidate Petro Poroshenko and his wife Maryna hold their ballot papers by voting booths at a polling station during the second round of Ukraine's presidential election in Kiev on April 21, 2019. (Photo by Sergei GAPON / AFP)

Ukrainian President and presidential candidate Petro Poroshenko walks out of a voting booth at a polling station during the second round of Ukraine's presidential election in Kiev on April 21, 2019. (Photo by Sergei GAPON / AFP)

Ukrainian President and presidential candidate Petro Poroshenko addresses the media at a polling station during the second round of Ukraine's presidential election in Kiev on April 21, 2019. (Photo by Sergei GAPON / AFP)

Ukrainian President and presidential candidate Petro Poroshenko and his wife Maryna visit a polling station during the second round of Ukraine's presidential election in Kiev on April 21, 2019. (Photo by Sergei GAPON / AFP)

Ukrainian President and presidential candidate Petro Poroshenko visits a polling station during the second round of Ukraine's presidential election in Kiev on April 21, 2019. (Photo by Sergei GAPON / AFP)

Ukrainian President Petro Poroshenko (C) holds his ballot paper to cast into a ballot box at a polling station during the second round of Ukraine's presidential election in Kiev on April 21, 2019. (Photo by Sergei SUPINSKY / AFP)

Ukrainian President Petro Poroshenko (R) holds his ballot paper to cast into a ballot box at a polling station during the second round of Ukraine's presidential election in Kiev on April 21, 2019. (Photo by Sergei SUPINSKY / AFP)

Ukrainian President Petro Poroshenko (L) and his wife Maryna Poroshenko hold their ballot papers to cast into a ballot box at a polling station during the second round of Ukraine's presidential election in Kiev on April 21, 2019. (Photo by Sergei SUPINSKY / AFP)

Ukrainian President Petro Poroshenko (L) and his wife Maryna Poroshenko cast their ballot papers into a ballot box at a polling station during the second round of Ukraine's presidential election in Kiev on April 21, 2019. (Photo by Sergei SUPINSKY / AFP)

Ukrainian President Petro Poroshenko holds his ballot paper as his wife Maryna leaves a polling booth to cast at a polling station during the second round of Ukraine's presidential election in Kiev on April 21, 2019. (Photo by Sergei SUPINSKY / AFP)

Ukrainian President Petro Poroshenko holds his ballot paper as his wife Maryna leaves a polling booth to cast at a polling station during the second round of Ukraine's presidential election in Kiev on April 21, 2019. (Photo by Sergei SUPINSKY / AFP)

Ukrainian President Petro Poroshenko (L) and his wife Maryna Poroshenko hold their ballot papers to cast into a ballot box at a polling station during the second round of Ukraine's presidential election in Kiev on April 21, 2019. (Photo by Sergei SUPINSKY / AFP)

Ukrainian President Petro Poroshenko (L) and his wife Maryna Poroshenko hold their ballot papers into a ballot box at a polling station during the second round of Ukraine's presidential election in Kiev on April 21, 2019. (Photo by Sergei SUPINSKY / AFP)

Ukrainian President Petro Poroshenko (L) and his wife Maryna Poroshenko (C) and their family cast their ballot papers to cast into a ballot box at a polling station during the second round of Ukraine's presidential election in Kiev on April 21, 2019. (Photo by Sergei SUPINSKY / AFP)

Ukrainian President Petro Poroshenko (L) and his wife Maryna Poroshenko (C) and their family cast their ballot papers to cast into a ballot box at a polling station during the second round of Ukraine's presidential election in Kiev on April 21, 2019. (Photo by Sergei SUPINSKY / AFP)

(190421) -- KIEV, April 21, 2019 (Xinhua) -- Candidate incumbent President Petro Poroshenko and his family cast their ballots at a polling station in Kiev, Ukrain, April 21, 2019. Ukraine s presidential candidates, incumbent President Petro Poroshenko and actor Volodymyr Zelensky, on Sunday cast their ballots in the second round of the country s presidential election. (Xinhua) UKRAINE-KIEV-PRESIDENTIAL ELECTION-2ND ROUND PUBLICATIONxNOTxINxCHN

(190421) -- KIEV, April 21, 2019 (Xinhua) -- Candidate incumbent President Petro Poroshenko speaks after casting his ballot at a polling station in Kiev, Ukrain, April 21, 2019. Ukraine s presidential candidates, incumbent President Petro Poroshenko and actor Volodymyr Zelensky, on Sunday cast their ballots in the second round of the country s presidential election. (Xinhua) UKRAINE-KIEV-PRESIDENTIAL ELECTION-2ND ROUND PUBLICATIONxNOTxINxCHN

KIEV, UKRAINE - APRIL 21: Ukrainian President and presidential candidate Petro Poroshenko casts his vote at a polling station during the second round of Ukraine's presidential election, in Kiev, Ukraine on April 21, 2019. Vladimir Shtanko / Anadolu Agency/ABACAPRESS.COM

KIEV, UKRAINE - APRIL 21: Ukrainian President and presidential candidate Petro Poroshenko casts his vote at a polling station during the second round of Ukraine's presidential election, in Kiev, Ukraine on April 21, 2019. Vladimir Shtanko / Anadolu Agency/ABACAPRESS.COM

KIEV, UKRAINE - APRIL 21: Ukrainian President and presidential candidate Petro Poroshenko casts his vote at a polling station during the second round of Ukraine's presidential election, in Kiev, Ukraine on April 21, 2019. Vladimir Shtanko / Anadolu Agency/ABACAPRESS.COM

KIEV, UKRAINE - APRIL 21: Ukrainian President and presidential candidate Petro Poroshenko casts his vote at a polling station during the second round of Ukraine's presidential election, in Kiev, Ukraine on April 21, 2019. Vladimir Shtanko / Anadolu Agency/ABACAPRESS.COM