# include <stdio.h>

int main()
{
    int sum = 0;
    int score[5] = { 0 };
    //数组输入
    for (int i = 0; i < 5; i++)
    {
        scanf("%d", &score[i]);
        sum += score[i];
    }
    double avg = sum / 5.0;
    //输出
    printf("%.1lf\n", avg);

    return 0;
}