#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;
}