func_code_string: #include <bits/stdc++.h>   using namespace std;   long long t = 1, T;   void print2d(vector<vector<long long>> &v) {     for (long long i = 0; i < v.size(); i++) {       for (long long x : v[i]) {         cout << x <<    ;       }       cout <<   n ;     }   }   void print(vector<long long> &a) {     for (long long x : a) {       cout << x <<    ;     }     cout <<   n ;     return;   }   long long fun(long long x, long long y) { return x * x + y * y; }   void solve() {     long long n;     cin >> n;     vector<long long> a(n, 0);     vector<long long> freq(n + 1, 0);     long long x;     for (long long i = 0; i < n; i++) {       cin >> a[i];       freq[a[i]]++;     }     set<long long> v;     for (long long i = 0; i < n; i++) {       for (long long j = i + 1; j < n; j++) {         v.insert(a[i] + a[j]);       }     }     long long ans = 0;     for (long long sum : v) {       long long i, j;       if (sum & 1) {         i = sum / 2;         j = i + 1;       } else         i = j = sum / 2;       long long rep = 0;       while (i >= 1 && j <= n) {         if (i == j) {           rep += freq[i] / 2;           i--;           j++;         } else {           rep += min(freq[i], freq[j]);           i--;           j++;         }       }       ans = max(ans, rep);     }     cout << ans <<   n ;   }   int32_t main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     cout.tie(NULL);     cin >> t;     T = t;     while (t--) {       solve();     }     return 0;   }   