#include <bits/stdc++.h>
using namespace std;
long long n, h, mx, c, a, b[100005];
int main() {
  long long i;
  cin >> n >> h;
  for (i = 0; i < n; i++) scanf("%lld %lld", &a, &b[i]), mx = max(mx, a);
  for (i = 0; i < n; i++)
    if (b[i] > mx && h > 0) h -= b[i], c++;
  if (h > 0) c += (h + mx - 1) / mx;
  cout << c << endl;
  return 0;
}
