#include <bits/stdc++.h>
using namespace std;
int N, H;
vector<int> A, B;
void input() {
  cin >> N >> H;
  A = B = vector<int>(N);
  for (int i = 0; i < (int)(N); i++) cin >> A[i] >> B[i];
}
int main() {
  input();
  int m = *max_element(A.begin(), A.end());
  int ans = 0;
  for (int i = 0; i < (int)(N); i++) {
    if (H > 0 && B[i] > m) {
      H -= B[i];
      ans++;
    }
  }
  if (H > 0) ans += (H - 1) / m + 1;
  cout << ans << endl;
}
