#include <bits/stdc++.h>
using namespace std;
int main() {
  long long N, M;
  long long ans = 0;
  cin >> N >> M;
  vector<long long> A(N);
  vector<long long> B(N);
  for (int i = 0; i < N; i++) cin >> A.at(i) >> B.at(i);
  long long maxA = 0;
  for (int i = 0; i < N; i++) maxA = max(maxA, A.at(i));
  for (int i = 0; i < N; i++) {
    if (B.at(i) > maxA) {
      ans++;
      M -= B.at(i);
    }
  }
  ans += (M + maxA - 1) / maxA;
  cout << ans << endl;
}
