#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, h;
  cin >> n >> h;
  vector<int> a(n), b(n);
  int ap = h;
  int r = 0;
  for (int i = 0; i < n; i++) {
    int ai, bi;
    cin >> ai >> bi;
    a.at(i) = ai;
    b.at(i) = bi;
    ap -= bi;
    r = max(r, ai);
  }
  sort(b.begin(), b.end());
  int ans = ap / r;
  int h0 = h - ans * r;
  if (h0 > h - ap) {
    h0 -= r;
    ans++;
  }
  while (h0 > 0) {
    int attack = b.at(b.size() - 1);
    b.pop_back();
    if (attack > r) {
      h0 -= attack;
      ans++;
    } else {
      b.push_back(attack);
      h0 -= r;
      ans++;
    }
  }
  cout << ans << endl;
}
