#include<stdio.h>
int main()
{
    int n;
    scanf("%d,&n");
    if(n<=0)
    {
        printf("No readings provided");
        return 0;
    }
    int a;
    float sum=0.0;
    for(int i=0;i<n;i++)
    {
        scanf("%d",&a);
        sum+=a;
    }
    float average=sum/n;
    printf("%.2f",average);
    return 0;
}