#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;
}