#include <bits/stdc++.h>
using namespace std;
vector<int> vec;
int main() {
  int n = 0, t = 0;
  cin >> n >> t;
  for (int i = 0; i < n; ++i) {
    int temp1 = 0, temp2 = 0;
    cin >> temp1 >> temp2;
    for (; temp1 < t; temp1 += temp2)
      ;
    vec.push_back(temp1);
  }
  vector<int>::iterator ans =
      find(vec.begin(), vec.end(), *min_element(vec.begin(), vec.end()));
  cout << distance(vec.begin(), ans) + 1;
  return 0;
}
