#include<bits/stdc++.h>
using namespace std;
 
int drunkOrNot(vector<pair<int, int>>& alcohol, long unsigned int limit) {
  long unsigned int total = 0;
 
  for(long unsigned int i = 0; i < alcohol.size(); i++) {
    long unsigned int val = alcohol[i].first*alcohol[i].second/100;
    total += val;
    if(total > limit)
      return i + 1;
  }
  return -1;
}
 
int main() {
  long unsigned int N, X;
  cin >> N;
  cin >> X;
 
  vector<pair<int, int>> alcohol;
 
  for(long unsigned int i = 0; i < N; i++) {
    int v1, v2;
    cin >> v1;
    cin >> v2;
    alcohol.push_back({v1, v2});
  }
 
  cout << drunkOrNot(alcohol, X) << endl;
}

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