#include <bits/stdc++.h>
using namespace std;
int w[100005];
int t[100005];
int main() {
  int n;
  long long m;
  cin >> n >> m;
  long long wmax = 0;
  for (int i = 1; i <= n; i++) {
    cin >> w[i] >> t[i];
    if (w[i] > wmax) wmax = w[i];
  }
  sort(t + 1, t + n + 1);
  long long ans = 0;
  for (int i = n; i > 0; i--) {
    if (m >= 0) {
      if (t[i] > wmax) {
        ans++;
        m = m - t[i];
      } else {
        ans = ans + m / wmax;
        if (m % wmax != 0) ans++;
        m = 0;
      }
    }
  }
  cout << ans << endl;
}
