#include <bits/stdc++.h>
using namespace std;
int main() {
  int N;
  int H;
  int x;
  cin >> N >> H;
  int a[100010], b[100010];
  for (int i = 0; i < N; i++) {
    cin >> a[i] >> b[i];
    a[i] = max(a[i], a[i + 1]);
    x = a[i];
  }
  sort(b, b + N);
  int ans = 0;
  for (int j = N; j >= 0; j--) {
    if (x <= b[j] and H > 0) {
      H = H - b[j];
      ans++;
    }
  }
  if (H > 0) ans += (H + x - 1) / x;
  cout << ans << endl;
  system("pause");
  return 0;
}
