#include <bits/stdc++.h>
using namespace std;
typedef struct data {
  int now;
  int cost;
} data;
int nw[9] = {0, 1, 0, -1, -1, 1, 1, -1, 0};
int nh[9] = {1, 0, -1, 0, 1, 1, -1, -1, 0};
int main() {
  long long int n, h;
  vector<pair<long long int, int> > atack;
  cin >> n >> h;
  for (long long int i = 0; i < n; i++) {
    long long int a, b;
    cin >> a >> b;
    atack.push_back(pair<long long int, int>(a, 0));
    atack.push_back(pair<long long int, int>(b, 1));
  }
  return 0;
  sort(atack.begin(), atack.end(), greater<pair<long long int, int> >());
  long long int ans = 0, sum = 0;
  while (sum < h) {
    if (atack[0].second == 1) {
      ans++;
      sum += atack[0].first;
      atack.erase(atack.begin());
    } else if (atack[0].second == 0) {
      ans += (h - sum) / atack[0].first + ((h - sum) % atack[0].first ? 1 : 0);
      sum = h + 1;
      break;
    }
  }
  cout << ans << endl;
  return 0;
}
