#include <bits/stdc++.h>
typedef long long ll;
using namespace std;
ll tc, a, b, c, ar[53];
ll fun (ll n){
ll tmp = 0;
for(int k = 1; k<= n/2 ; k++){
if(k*2 == n){
tmp += ar[k]/2;
}
else if(ar[k] > 0 && ar[n - k] > 0){
tmp += min(ar[k], ar[n - k]);
}
}
return tmp;
}
int main() {
scanf("%lld", &tc);
while(tc--){
scanf("%lld", &a);
memset(ar, 0, sizeof(ar));
ll maks = 1;
for(int k = 1; k<= a; k++){
scanf("%lld", &b);
ar[b]++;
}
if(a == 1){
printf("0\n");
continue;
}
for(ll k = 2; k<= 2*a; k++){
ll tmp = fun(k);
maks = max(maks, tmp);
}
printf("%lld\n", maks);
}
}
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