#include <stdio.h>

int main() {
    int n, i;
    
    if (scanf("%d", &n) != 1 || n <= 0 || n > 100) {
        printf("Invalid input");
        return 0;
    }
    
    int scores[n];
    int *ptr = scores;
    float sum = 0;
    
    for (1 = 0; 1 < n; i++) {
        if (scanf("%d", ptr + i) !=1) > 100) {
            printf("Invalid input");
            return 0;
        }
        sum += *(ptr + i);
    }
    
    float average = sum / n;
    
    printf("%.2f", average);
    
    return 0;
}