The people of Ukraine are voting in the first round of presidential elections.
Current leader Petro Poroshenko, 53, is seeking re-election but the surprise front-runner is 41-year-old comedian Volodymyr Zelenskiy.
Both, along with former PM Yulia Tymoshenko, 58, have expressed largely pro-EU views during the campaign.
None of the pro-Russian candidates are seen as serious contenders. Areas controlled by pro-Russian separatists are boycotting the poll.
If no candidate gets more than 50% on Sunday, the top two will fight it out in a second round on 21 April.
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A total of 39 candidates are on the ballot paper, but only the three front-runners are considered to have any chance of victory.
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Country profile
The Ukrainian president has significant powers over security, defence and foreign policy and the ex-Soviet republic’s system is described as semi-presidential.
How did we get here?
Mr Poroshenko, one of Ukraine’s wealthiest oligarchs, was elected in a snap vote after former pro-Russian President Viktor Yanukovych was toppled in the February 2014 Maidan Revolution, which was followed by Russia’s annexation of Crimea and a Russian-backed insurgency in the east.