#include <bits/stdc++.h>
using namespace std;
long long H;
int n, a[100100], b[100100], amax = -1, d[100100], ok = 0, cnt, i, ans;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cin >> n >> H;
  for (i = 1; i <= n; i++) {
    cin >> a[i] >> b[i];
    amax = max(amax, a[i]);
  }
  sort(b + 1, b + n + 1);
  for (i = 1; i <= n; i++) {
    if (b[n - i + 1] > amax) {
      d[++cnt] = d[i - 1] + b[n - i + 1];
      if (d[cnt] >= H) goto num1;
    } else
      break;
  }
  while (d[cnt] < H) {
    d[cnt + 1] = d[cnt] + amax;
    cnt++;
  }
num1:
  cout << cnt << endl;
  return 0;
}
