#include<stdio.h>
int main()
{
    int N,ind;
    float avg,sum;
    scanf("%d",&N);
    if(N<0 || !(scanf("%d",&N))
    {
        printf("Invalid input");
        return 0;
    }
    int marks[N];
    for(ind=0;ind<N;ind++)
    {
        scanf("%d",&marks[ind]);
        sum+=marks[ind];
    }
    avg=sum/N;
    printf("%.2f",avg);
    return 0;
}