#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;
}