#include<stdio.h>
int main(){
    int T;
    scanf("%d",&T);

    int  total_score=0;
    for(int i=0;i<T;i++){
        int s,n;
        scanf("%d %d",&s,&n);
        int m=s*7/10;
        for(int o=0; o<n;o++){
            s=s*95/100;
        }
        if(m>s){
            total_score+=m;
        }else(total_score+=s);
        
    }
    printf("%d",total_score);
    return 0;
}

#include<iostream>
using namespace std;
int main()
{   int t;
    int s[105],n[105];
    cin>>t;
    int sum = 0;
    for(int i = 1;i <= t;i++)
    {
      cin>>s[i]>>n[i];
      int u = s[i];
     if(n[i]) for(int j = 1;j <= n[i];j++)u= u*95/100;
      int r = s[i]*7/10;
      sum += max(u,r);
    }
    printf("%d",sum);
    return 0;
}