#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int H, W;
  cin >> H >> W;
  vector<long long int> A(H), B(H), C(H), D(H);
  for (int i = 0; i < H; i++) {
    cin >> A[i] >> B[i];
    C[i] = A[i];
    D[i] = B[i];
  }
  sort(A.begin(), A.end());
  long long int x = A[H - 1], sum = 0;
  int j = -5, l = -5;
  sort(B.rbegin(), B.rend());
  for (int i = 0; i < H; i++) {
    if (B[i] <= x) {
      l = i;
      break;
    }
    sum += B[i];
    if (sum >= W) {
      j = i;
      break;
    }
  }
  if (j >= 0)
    cout << j + 1 << endl;
  else {
    cout << (W - sum + x - 1) / x + l << endl;
  }
}
