#include<stdio.h>
int main() {
    int n, temp;
    float sum = 0,
    scanf("%d", &n);
    if (n <= 0) {
        printf("No readings");
        return 0;
    }
    for (int i = 0; i < n; i++) {
        scanf("%d", &temp);
        sum += temp;
    }
    printf("%.2f", sum / n);
    return 0;
}