#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9;
const int D_MAX = 10;
int p[D_MAX+1], c[D_MAX+1];
int D, G;

int dfs(int s, int g, int a){
  if(s == D + 1){
    if(g <= 0 || a == 0) return 0;
    if(g - a*100*(p[a]-1) > 0) return INF;
    return (g + a*100 - 1)/(a*100);
  }
  return min(dfs(s+1, g-100*s*p[s]-c[s], a) + p[s] , dfs(s+1, g, s));
}

int main(){
  cin >> D >> G;
  for(int i = 1; i <= D; i++){
    cin >> p[i] >> c[i];
  }
  cout << dfs(1, G, 0) << endl;
  return 0;
}
