#include <bits/stdc++.h>
using namespace std;
int main() {
  long long N, H, sum = 0;
  cin >> N >> H;
  long long a, b[N], A = 0, n = 0;
  for (int i = 0; i < N; i++) {
    cin >> a >> b[i];
    A = max(A, a);
  }
  for (int i = 0; i<N; n += b[i++]> A) {
    if (b[i] > A) {
      sum += b[i];
    }
    if (sum >= H) {
      cout << n + 1;
      return 0;
    }
  }
  n += (H - sum - 1) / A + 1;
  cout << n;
}
