// editor5
#include <stdio.h>
int main(){
    int n;
    double t,s=0.0;
    if(scanf("%d", &n)!=1){
        printf("Invalid input\n");
        return 1;
        
    }
    if(n<=0){
        printf("No readings provided\n");
        return 1;
    }
    for(int i=0;i<n;i==){
        if(scanf("%lf",&t)!=1){
            printf("Invalid input\n");
            return 1;
        }
        s+=t;
    }
    double avg=s/n;
    printf("%.2f\n",avg);
    return 0;
}