我很菜，不喜勿喷

#include <bits/stdc++.h>
using namespace std;
int main(){
int n;
cin >> n;
int a[n+1];
for(int i=0;i<n;i++){
cin >> a[i];
}
sort(a,a+n,greater<int>());
a[n]=0;
int sum1 = a[0];
for (int i=3;i<n;i=i+4)
{
sum1 = sum1+a[i]+a[i+1];
}
int sum2 = 0;
for (int i=1;i<n;i=i+4)
{
sum2 = sum2+a[i]+a[i+1];
}
int res;
res = sum1 - sum2;
if (res>=0) cout << res<<" ";
else cout << -res<<" ";

return 0;

}