<?php
list($a, $b, $c, $d) = explode(" ", trim(fgets(STDIN)));
for ($yasai = 1; $yasai <= $a; $yasai++) {
  $total = $yasai + ($yasai * $c);
  if ($total > $d) {
    echo ($yasai - 1)."\n";
    break;
  } elseif (($yasai * $c) > $b) {
    echo ($yasai - 1)."\n";
    break;
  }
}