#include <stdio.h>
#define Size 3

double average(int nums[], int size) {
    double total = 0;
    for(int i = 0; i < size; i++) {
        total += nums[i];
    }
    return total / size;
}

int main() {
    int nums[Size] = {0};
    scanf("%d%d%d", &nums[0], &nums[1], &nums[2]);
    printf("%.6f", average(nums, Size));
    return 0;
}