#include <bits/stdc++.h>
using namespace std;
const long long INF = 1e9;
int main() {
  long long N, H;
  cin >> N >> H;
  vector<long long> a(N), b(N);
  for (long long i = 0; i < N; i++) cin >> a[i] >> b[i];
  b.push_back(-INF);
  sort(a.begin(), a.end(), greater<long long>());
  sort(b.begin(), b.end(), greater<long long>());
  long long res = 0;
  while (H > 0) {
    for (auto it : b) {
      if (it > a[0]) {
        res++;
        H -= it;
      } else {
        res += ceill((long double)H / (long double)a[0]);
        H -= H;
      }
    }
  }
  cout << res << endl;
}
