#include <stdio.h>

int main()
{
    float sum = 0.0;
    float arr[5] = { 0.0 };
    for (int i = 0; i < 5; i++)
    {
        scanf("%f", &arr[i]);
        sum += arr[i];
    }
    //输出
    printf("%.2f\n", sum / 5.0);

    return 0;
}