#include<stdio.h>
int main()
{
    long x[20],ans=0;
    int i=0,n=0;
    int j=0;
    long tmp=0,p[2];
    scanf("%ld",&n);
    for(i=0;i<n;i++) scanf("%ld",&x[i]);
    for(i=0;i<n;i++)
    {
        for(j=i+1;j<n;j++) if(x[j-1]<x[j])
        {
            tmp=x[j];
            x[j]=x[j-1];
            x[j-1]=tmp;
        }
    }
    for(i=0;i<n;i++)
    {
        if(i<2) p[i]=x[i];
        else if(p[0]>p[1]) p[1]+=x[i];
        else p[0]+=x[i];
    }
    ans=p[1]-p[0];
    if(ans<0) ans=-ans;
    printf("%ld\n",ans);
}
My code worked all of my test cases.

5
6
6
6
9
9

correct answer is 0