#include<stdio.h>
int main()
{
    int size,ind ;
    float sum=0;
    scanf("%d",&size);
    if(!scanf("%d",&size)!=1||size<1||size>100);
    {
        printf("Invalid input");
        return 0;
    }
    int stud[size];
    for(ind=0;ind<size;ind++)
    {
        scanf("%d",&stud[ind]);
    }
    for(ind=0;ind<size;ind++)
    {
        if{
            (scanf("%d",&stud[ind]!=0||stud[ind]<1||stud[ind]>100))
            return 0;
        }
        sum += stud[ind];
    }
    float avg=sum/size;
    printf("%.2f",avg);
    return 0;
}