#include <bits/stdc++.h>
using namespace std;
int main() {
  int N, H;
  cin >> N >> H;
  vector<long> a(N), b(N);
  for (int i = 0; i < N; i++) cin >> a[i] >> b[i];
  long max_a = 0;
  for (int i = 0; i < N; i++) {
    if (max_a < a[i]) max_a = a[i];
  }
  int than_count = 0;
  long dif = 0;
  for (int i = 0; i < N; i++) {
    if (max_a < b[i]) {
      than_count++;
      dif += b[i] - max_a;
    }
  }
  long ans = (H + max_a - 1) / max_a;
  long H_tmp = max_a * ans + dif;
  int sub_count = 0;
  while (H_tmp - max_a >= H) {
    sub_count++;
    H_tmp -= max_a;
  }
  cout << ans - sub_count << endl;
  return 0;
}
