#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
int N, H;
int a[100010], b[100010];
int maxa;
int main() {
  cin.tie(0);
  ios_base::sync_with_stdio(false);
  cout << fixed << setprecision(10);
  cin >> N >> H;
  for (int i = 0; i < N; i++) {
    cin >> a[i] >> b[i];
    maxa = max(maxa, a[i]);
  }
  int ans = 0;
  for (int i = 0; i < N; i++) {
    if (H > 0 && b[i] > maxa) {
      H -= b[i];
      ans++;
    }
  }
  if (H > 0) ans += (H + maxa - 1) / maxa;
  cout << ans << endl;
  return 0;
}
