#include<bits/stdc++.h>
using namespace std;

int p[10],c[10];

signed main(){

  int D,G; cin >> D >> G;
  for(int i = 0; i < D; i++){
    cin >> p[i] >> c[i];
  }

  int ans = 1145141919;
  for(int i = 0; i < (1 << D); i++){
    int t = 0,cnt = 0;
    for(int j = 0; j < D; j++){
      if(1 & (i >> j)){
        t += p[j]*(j+1)*100 + c[j];
        cnt += p[j];
      }
    }

    for(int j = D-1; j >= 0; j--){
      if(1 & (i >> j)) continue;
      if(G <= t) break;
      int need = min((G-t)/((j+1)*100),p[j]);
      t += need*(j+1)*100;
      cnt += need;
    }
    ans = min(ans,cnt);
  }
  cout << ans << endl;

  return 0;
}
