#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, h;
  cin >> n >> h;
  long long a[n];
  long long b[n];
  long long max_a = 0;
  long long hp = h;
  long long ans = 0;
  for (int i = 0; i < n; i++) {
    cin >> a[i] >> b[i];
    if (max_a < a[i]) max_a = a[i];
  }
  for (int i = 0; i < n; i++) {
    if (max_a < b[i]) {
      hp -= b[i];
      ans++;
    }
    if (hp <= 0) break;
  }
  if (hp > 0) ans += (hp + max_a - 1) / max_a;
  cout << ans << endl;
}
