<?php
[$a,$b,$c,$d,$m] = explode(" ",trim(fgets(STDIN)));

$e = $a+$c;
$f = $b+$d;
$ans = $m % $f;

for($i = $f;$i >= $e;$i--){
    $mod[$i] = $m % $f;
    if ($mod[$i] >= $mod[$i+1]) {
        $ans = $mod[$i];
    }
}

echo $ans;
?>