#include <stdio.h>
#include <stdlib.h>

///Add the struct for my list which i need to put in input values.
struct list
{
    double number;
    struct list *next;
};

typedef struct list LIST;

LIST *top = NULL;
LIST *tmp = NULL;


///Function to add the new Input Value and the List and link them together.
///Allocates Memory for the new Nodes in the List.
void add_element(double number)
{
    if(top == NULL)
    {
        top = (LIST *)malloc(sizeof(LIST));
        top->number = number;
        top->next = NULL;
    }
    else
    {
        tmp = (LIST *)malloc(sizeof(LIST));
        tmp->next = top;
        tmp->number = number;
        top = tmp;
    }
}


///Count the single Positions in the List and return the Number of Values inside.
int size(LIST *i)
{
    int size = 0;
    for(i = top; i != NULL; i = i->next)
    {
        size ++;
    }
    return size;
}


///Calculate all Values in the List and return the sum of all of them.
double sum(LIST *i)
{
    double value = 0;
    for(i = top; i != NULL; i = i->next)
    {
        value = i->number+value;
    }
    return value;
}


///Clears the memory of the last value in the list and link the list again to the previous value.
void clear_list()
{
    if(top->next == NULL)
    {
        free(top);
        top = NULL;
    }
    else
    {
        LIST *n = top->next;
        free(top);
        top = n;
    }

}

int main()
{
    double input;
    double temp;
    double durchschnitt;

    ///Scan the Value the User want to calculate until the Input is <= 0.
    while(input > 0.0000)
    {
        scanf("%lf", &input);
        add_element(input);
    }

    ///Cleared the last value in the List with which the User canceled the Input.
    clear_list();

    ///Calculate the Average of the Input Numbers.
    durchschnitt = sum(top)/size(top);

    ///Find out which Numbers are smaller than average and write the sum on an double int.
    for(LIST *i = top; i != NULL; i = i->next)
    {
        if(i->number < durchschnitt)
        {
            temp = temp + i->number;
        }
    }

    printf("%.2f", temp);

    ///Free the memory which was allocated for the Input list.
    for(LIST *i = top; i != NULL; i = i->next)
    {
        clear_list();
    }

    return 0;
}