#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, t, c = 1;
  cin >> n >> t;
  int mn = INT_MAX;
  for (int i = 1; i <= n; i++) {
    int s, d;
    cin >> s >> d;
    while (s < t) {
      s += d;
    }
    if (s < mn) {
      mn = s;
      c = i;
    }
  }
  cout << c << endl;
  return 0;
}
