#include<stdio.h>
#include<string.h>
#define N 10
#define MAX_LEN 10
int main()
{
struct stu
{
int number;
char name[N] ;
int score ;
};
struct stu student[N] ;
int i ,n ;
float aver = 0,sum = 0;
scanf("%d",&n) ;
for(i = 0 ;i < n; i++)
{
scanf("%d %s %d",&student[i].number,&student[i].name,&student[i].score);
getchar();
sum += student[i].score ;
}
aver = sum /n ;
printf("%.2f",aver);
return 0 ;
}