<?php
fscanf(STDIN, "%d %d", $n, $h);
while ($n--) {
	fscanf(STDIN, "%d %d", $a[], $b[]);
}
$m = max($a);
$x = $s = 0;
foreach ($b as $c) {
	if ($c > $m) {
		$x++;
		$h -= $c;
	}
}
if ($h > 0) $x += ceil($h / $m);
echo $x;