#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int N, H;
  cin >> N >> H;
  vector<int> a(N), b(N);
  vector<pair<int, int>> p(N);
  for (int i = 0; i < N; i++) {
    cin >> a[i] >> b[i];
    p[i] = make_pair(b[i], a[i]);
  }
  sort(p.begin(), p.end());
  reverse(p.begin(), p.end());
  int Count = 0;
  int i = 0;
  while (H > 0) {
    if (i == N - 1) {
      Count += (H - p[i].first) / p[i].second + 1;
      H = 0;
    } else {
      if (p[i + 1].first >= p[i].second) {
        H -= p[i].first;
        Count++;
        i++;
      } else {
        Count += (H - p[i].first) / p[i].second + 1;
        H = 0;
      }
    }
  }
  cout << Count << endl;
}
