#include <bits/stdc++.h>
using namespace std;
int N, H, A[100000], B[100000];
int main() {
  cin >> N >> H;
  for (int i = 0; i < N; i++) cin >> A[i] >> B[i];
  int maxAi = 0;
  for (int i = 0; i < N; i++) {
    maxAi = max(maxAi, A[i]);
  }
  int64_t ans = 0;
  for (int i = 0; i < N; i++) {
    if (maxAi < B[i]) {
      H -= B[i];
      ans++;
    }
    if (H <= 0) break;
  }
  if (0 < H) {
    ans += H / maxAi;
    if (0 < H % maxAi) ans++;
  }
  cout << ans << endl;
}
