#include <stdio.h>
#include <stdlib.h>

int main(){
    int N;
    int i;
    int *scores;
    long long sum =0;
    double avg;
    
    if(scanf("$d", &N)!=1){
        printf("Invalid input");
        return 0;
    }
    
    if(N<1 || N>100){
        printf("Invalid input");
        return 0;
    }
    
    scores = (int *)malloc(N * sizeof(int));
    if(scores == NULL){
        return 1;
    }
    
    for(i=0; i<N; i++){
        if(scanf("%d",(scores+i))!=1){
            printf("Invalid input");
            free(scores);
            return 0;
        }
        if(*(scores + i)<)){
            printf("Invalid input");
            free(scores);
            return 0;
        }
        sum+=*(scores + i);
    }
    avg = (double)sum/N;
    printf("%.2f\n",avg)
}