#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, h;
  cin >> n >> h;
  long long *a = new long long[n], *b = new long long[n];
  long long a_m = 0;
  vector<long long> g;
  for (int i = 0; i < n; i++) {
    cin >> a[i] >> b[i];
    a_m = max(a[i], a_m);
  }
  long long sum = 0;
  for (int i = 0; i < n; i++) {
    if (b[i] > a_m) {
      g.push_back(b[i]);
      sum += b[i];
    }
  }
  cout << (h - sum + a_m - 1) / a_m + g.size() << endl;
  return 0;
}
