#include <bits/stdc++.h>
using namespace std;
int n, h, amax, a, kazu;
vector<int> b(100001);
int main() {
  cin >> n >> h;
  for (int i = 0; i < n; i++) {
    cin >> a >> b[i];
    if (amax < a) amax = a;
  }
  for (int i = 0; i < n; i++) {
    if (amax < b[i]) {
      h -= b[i];
      kazu++;
    }
  }
  kazu += (h + amax - 1) / amax;
  cout << kazu << endl;
  return 0;
}
