#include<stdio.h>
typedef struct student{
    float average;
}
int main(){
    int n,i;
    scanf("%d",&n);
    if(n<0||!scanf("%d",&n)){
        printf("Invalid input");
        return 0;
    }
    int arr[n];
    for(i=0;i<n;i++);{
        scanf("%d",&arr[i])
    }
    average = (arr[0]+arr[1]+arr[2]+arr[3]+arr[4])/5
    printf("%.2f",average);
    return 0;
}