#include <bits/stdc++.h>
using namespace std;
void solve() {
  long long N, H;
  cin >> N >> H;
  long long max = 0, sum = 0;
  vector<long long> a(N), b(N);
  for (int i = 0; i < (N); i++) {
    long long s, t;
    cin >> s >> t;
    if (max < s) max = s;
    a[i] = s;
    b[i] = t;
  }
  long long count = 0;
  for (int i = 0; i < (N); i++) {
    if (b[i] <= max) {
      a[i] = 0;
      b[i] = 0;
    } else
      count++;
    sum += b[i];
  }
  H -= sum;
  while (H > 0) {
    H -= max;
    count++;
  }
  cout << count << endl;
}
int main() {
  cin.tie(nullptr);
  ios_base::sync_with_stdio(false);
  cout << fixed << setprecision(20);
  solve();
  return 0;
}
