#include <bits/stdc++.h>
using namespace std;
long long n, h, a, b, mx = 0, total = 0, moves = 0, A = 0;
map<long long, long long, greater<long long>> throws;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cin >> n >> h;
  for (int i = 0; i < n; i++) {
    cin >> a >> b;
    if (mx < a) mx = a;
    throws[b]++;
  }
  for (auto it = throws.begin(); it != throws.end(); ++it) {
    if (it->first < mx) break;
    total += (it->first * it->second);
    moves += (1 * it->second);
  }
  if (total < h) {
    A = (h - total) / mx;
    if ((h - total) % mx != 0) A++;
  }
  cout << moves + A;
  return 0;
}
