#include <bits/stdc++.h>
int main() {
  static long long aa[100000], bb[100000];
  long long n, h, i, a, ans;
  scanf("%lld%lld", &n, &h);
  a = 0;
  for (i = 0; i < n; i++) {
    scanf("%lld%lld", &aa[i], &bb[i]);
    if (a < aa[i]) a = aa[i];
  }
  ans = 0;
  for (i = 0; i < n; i++)
    if (bb[i] > a && h > 0) {
      h -= bb[i];
      ans++;
    }
  if (h > 0) ans += (h + a - 1) / a;
  printf("%lld\n", ans);
  return 0;
}
