<?php
list($vege, $meat, $double, $count) = explode(" ",trim(fgets(STDIN)));
for($i = $vege; $i>=0; $i--){
    if($meat - ($i * $double) >= 0){
        if($count - ($i + ($i * $double)) >= 0){
            echo $i;
            exit;
        }
    }
}
echo 0;