#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int64_t N, H;
  cin >> N >> H;
  vector<int64_t> A(N);
  vector<int64_t> B(N);
  int64_t maxA = 0;
  for (int i = 0; i < (N); ++i) {
    cin >> A[i] >> B[i];
    maxA = max(maxA, A[i]);
  }
  int64_t B_SUM = 0;
  int64_t answer = 0;
  for (int i = 0; i < (N); ++i) {
    if (maxA < B[i]) {
      B_SUM += B[i];
      ++answer;
    }
  }
  H -= B_SUM;
  answer += (H + maxA - 1) / maxA;
  cout << answer << endl;
  return 0;
}
