#include <stdio.h>
int main()
{
    float stl[5];
    int i = 0;
    float average, sum = 0.0;
    for (i = 0; i < 5; i++)
    {
        scanf("%f", &stl[i]);
        sum += stl[i];
    }
    average = sum / 5;
    printf("%.2f\n", average);

    return 0;
}