URI 1154 Solution

#include <stdio.h>

int main()

{

    int i=0,N=0;

    double s=0;

    while(N>=0)

     {

        scanf("%d",&N);

        s=s+N;

        i++;

     }

     if(N<0)

     {

         s=s-N;

     }

    printf("%.2lf
",s/(i-1));

    return 0;

}