<?php
$inCount = 10;
$total = 0;
$inSum = 0;
$nonNum = $inCount;

$stdin = trim(fgets(STDIN));
$inNumList = explode(' ', $stdin);
foreach ($inNumList as $key => $inNum) {
    $total += $key + 1;
    $inSum += $inNum;
    if ($total < $inSum) {
        $nonNum = $inNum -1;
        break;
    }
}
echo $nonNum."\n";