#include <stdio.h>

int main()
{
    int score[5] = {0};
    int i = 0, sum = 0;
    
    for(i = 0;i < 5;i++)
    {
        scanf("%d", &score[i]);
        sum += score[i];
    }
    
    double average = sum / 5.0;
    
    printf("%.1lf", average); //取小数点后一位,记得使用%.1lf
    
    return 0;
}