<?php
$input = explode(' ', trim(fgets(STDIN)));
$n = (int)$input[0];
$h = (int)$input[1];

$katana = [];
$c_max = 0;
for ($i=1; $i <= $n; $i++) { 
	$input = explode(' ', trim(fgets(STDIN)));
	$katana[$i] = [
		'cut' => (int)$input[0],
		'throw' => (int)$input[1],
	];
	$c_max = max($c_max, (int)$input[0]);
}

$count = 0;
for ($j=1; $j<=$n ; $j++) { 
	$tmp_k = $katana[$j];
	if ($tmp_k['throw']>$c_max) {
		$h -= $tmp_k['throw'];
		++$count;
	}
	if ($h <= 0) {
		break;
	}
}
if ($h>0) {
	$count += ceil($h / $c_max);
}
echo $count;
