#include <stdio.h>
int main()
{
    int n;
    scanf("%d",&n);
    int id;
    double salary,total =0.0;
    for(int i =0; i < n; i++)
    {
        scanf("%d  %11f",&id, &salary);
        total += salary;
    }
    printf("%.2f",total);
    return 0;
    
}