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