#include <bits/stdc++.h>
using namespace std;
long long n, h, a, b, mx = 0, pos = 0, total = 0, moves = 0;
set<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 (a > mx) {
      mx = a;
      pos = 0;
    }
    throws.insert(b);
  }
  auto it = throws.begin();
  while (total <= h) {
    if (*it >= mx) {
      total += *it;
      ++it;
      moves++;
    } else {
      if ((h - total) % mx != 0) {
        moves += ((h - total) / mx) + 1;
        total += (moves * mx) + mx;
      } else {
        moves += ((h - total) / mx);
        total += (moves * mx);
      }
    }
  }
  cout << moves;
  return 0;
}
