#include <bits/stdc++.h>
using namespace std;
void solve() {
  int n, t;
  while (cin >> n >> t) {
    int x, y;
    vector<pair<int, int> > a;
    vector<pair<int, int> > v;
    for (int i = 0; i < n; i++) {
      cin >> x >> y;
      a.push_back(make_pair(x, y));
    }
    for (int i = 0; i < n; i++) {
      while (a[i].first < t) a[i].first += a[i].second;
      v.push_back(make_pair(a[i].first, i));
    }
    sort(v.begin(), v.end());
    cout << (v[0].second) + 1 << endl;
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  solve();
}
