import java.util.*;
import java.lang.*;
import java.io.*;
class Codechef
{
{
/*
number of unordered quadruplets (i,j,k,l) such that b[i] + b[j] + b[k] + b[l] = 0
~ code by roshanadhav
*/
//O(n^4) ;
Scanner sc
= new Scanner
(System.
in) ; int n = sc.nextInt() ;
int arr[] = new int[n] ;
for(int i = 0 ; i < n ; i++) {
arr[i] = sc.nextInt() ;
}
for(int i = 0 ; i < n ; i++) {
for(int j = i + 1 ; j < n ; j++) {
for(int k = j + 1 ; k < n ; k++) {
for(int l = k+1 ; l < n ; l++) {
if(arr[i] + arr[j] + arr[k] + arr[l] == 0) count++ ;
}
}
}
}
}
}
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