#include <bits/stdc++.h>
using namespace std;
template <typename T1, typename T2>
inline void chmin(T1 &a, T2 b) {
  if (a > b) a = b;
}
template <typename T1, typename T2>
inline void chmax(T1 &a, T2 b) {
  if (a < b) a = b;
}
const int MOD = 1000000007;
void solve() {
  long long n, h;
  cin >> n >> h;
  vector<long long> a(n);
  vector<long long> b(n);
  for (long long i = 0; i < (n); ++i) cin >> a[i] >> b[i];
  sort(a.begin(), a.end());
  sort(b.begin(), b.end());
  long long l = a[n - 1];
  long long index = lower_bound(b.begin(), b.end(), l) - b.begin();
  long long ans = 0;
  long long damage = 0;
  while (h > damage) {
    if (index < n) {
      damage += b[index];
      index++;
      ans++;
    } else {
      long long temp = (h - damage + l - 1) / l;
      ans += temp;
      damage += (temp * l);
    }
  }
  cout << ans << endl;
}
int main() {
  solve();
  return 0;
}
