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

int main(){

  long long d,g,p[11],c[11];
  cin>>d>>g;

  long long ans=1e9;

  for(int i=0;i<d;++i)cin>>p[i]>>c[i];

  for(int bit=0;bit<(1<<d);bit++){

    long long solv=0,point=0;

    for(int i=0;i<d;++i){

      if(bit&(1<<i)){

	solv+=p[i];
	point+=(i+1)*100*p[i]+c[i];

      }
      
    }

    if(bit==(1<<d)-1){

      ans=min(ans,solv);
      
    }else{

      for(int i=d-1;i>=0;--i){

	if(!(bit&(1<<i))){

	  if(point+(p[i]-1)*(i+1)*100>=g){

	    ans=min(ans,solv+max(0LL,(g-point+(i+1)*100-1)/((i+1)*100)));

	  }

	  break;

	}

      }

    }
    
  }

  cout << ans << endl;

  return 0;
}
