func_code_string: #include <bits/stdc++.h>   long long gcdfun(long long x, long long y) {     if (y == 0)       return x;     else       return gcdfun(y, x % y);   }   using namespace std;   int main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     int t;     cin >> t;     while (t--) {       int n, k = 1, flag = 0, ans = 0;       cin >> n;       vector<int> a(n), b(n);       for (int i = 0; i < n; i++) {         cin >> a[i];       }       sort(a.begin(), a.end());       int p = *max_element(a.begin(), a.end());       while (k <= 1024) {         flag = 0;         for (int i = 0; i < n; i++) {           b[i] = (a[i] ^ k);         }         sort(b.begin(), b.end());         for (int i = 0; i < n; i++) {           if (a[i] != b[i]) {             flag = 1;             break;           }         }         if (flag == 1)           k++;         else {           cout << k <<   n ;           ans = 1;           break;         }       }       if (ans == 0) cout << -1 <<   n ;     }   }   