#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, h;
  cin >> n >> h;
  int max = 0;
  vector<pair<int, int> > a(n);
  for (int i = 0; i < n; i++) {
    cin >> a[i].first >> a[i].second;
    if (a[i].first > max) max = a[i].first;
  }
  int cnt = 0, sum = 0;
  for (int i = 0; i < n; i++) {
    if (a[i].second > max) {
      cnt++;
      sum += a[i].second;
    }
  }
  if (sum < h) {
    cnt += (h - sum + max - 1) / max;
  }
  cout << cnt << endl;
  return 0;
}
