#include <stdio.h>
#include <stdlib.h>
int main(){
    int N;
    if (scanf("%d", &N) != 1) {
        printf("Invalid input");
        return 0;
    }
    
    if (N < 1 || N > 100){
        printf("Invalid input");
        return 0;
    }
    
    int sum = 0;
    
    
    ptr = scores;
    for (int i = 0; i < N; i++) {
        if (scanf("%d", ptr) != 1){
            printf("Invalid input");
            free(scores);
            return 0;
        }
        if (*ptr < -100 || *ptr > 100){
            printf("Invalid input");
            free(scores);
            return 0;
        }
        ptr++;
    }
    ptr = scores;
    for (int i = 0; i < N; i++){
        sum += *ptr;
        ptr++;
    }
    double average = (double)sum / N;
    printf("%.2f", average);
    return 0;
}