/* -*- coding: utf-8 -*-
 *
 * 3422.cc:  No.3422 Sazanka's hobby - yukicoder
 */

#include<cstdio>
#include<algorithm>

using namespace std;

/* constant */

const int MAX_N = 1000000;

/* typedef */

/* global variables */

int as[MAX_N], bs[MAX_N];
int ds[MAX_N];

/* subroutines */

bool check(int n, int k) {
  for (int i = 1; i * k < n; i++) {
    if (ds[i * k] <= i) return false;
  }
  return true;
}

/* main */

int main() {
  int n, m;
  scanf("%d%d", &n, &m);
  for (int i = 0; i < n; i++) scanf("%d%d", as + i, bs + i);

  for (int i = 0; i < n; i++) ds[i] = (m - as[i]) / bs[i] + 1;
  sort(ds, ds + n);

  int k0 = 0, k1 = n;
  while (k0 + 1 < k1) {
    int k = (k0 + k1) / 2;
    if (check(n, k)) k1 = k;
    else k0 = k;
  }

  printf("%d\n", k1);

  return 0;
}