#include <bits/stdc++.h>

using namespace std;
int main(){
  long d,g;
   cin >> d >> g;
  
  vector<long> p(d),c(d);
  long res=0;
  for(long i=0;i<d;i++){
    cin >> p[i] >> c[i];
    res+=p[i];
  }

  for(long i=0;i<(1<<d);i++){
    long score=0;
    long num=0;
    long rest=-1;
   for(long j=0;j<d;j++){
     if((i>>j)&1) {
       score+=(p[j]*100*(j+1)+c[j]);
       num+=p[j];
     }
     else{
      rest=j;
     } 
     }
    if(g>score){
      long need=min((g-score-1)/(100*(rest+1))+1,p[rest]);
       score+=100*(rest+1)*need;
       num+=need;
     }
    if(score>=g) res=min(res,num);
  }
  
  
  
cout << res << endl;

}
