#include<stdio.h>
void calculate_average(int count ,int reading[])
{
    if(count==0)
    {
        printf("No reading provided\n");
        return ;
    }
    int sum=0;
    for(int i=0;i<count;i++)
    {
        sum +=reading[i];
    }
    double average=(double)sum/count;
    printf("%.2f\n",average);
    
}
int main()
{
    int n;
    scanf("%d,&n");
    if(n==0)
    {
        printf("No reading provided\n");
        return 0;
    }
    int readings[100];
    for(int i=0;i<n;i++)
    {
        scanf("%d,&readings[i]");
    }
    calculate_average(n,readings);
    return 0;
}