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

int main()
{
   int count = 1;

   double *array = (double*)malloc(count*sizeof(double));

   int n=0;
    double last=0;

    while(last>=0){
    scanf("%lf",&last);

    if(last>=0){

        count++;
        array = (double*)realloc(array, count*sizeof(double));
        array[n]=last;
        n++;
    }
    }

    double sum=0;
    double smallsum=0;

    for(int i=0;i<=n;i++){
        sum=sum+array[i];
    }

    double mittelwert=sum/(n);


    for(int i=0;i<=n;i++){
        if(array[i]<mittelwert){
            smallsum=smallsum+array[i];
        }
    }


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




   free(array);




    return 0;
}