func_code_string: #include <bits/stdc++.h>   using namespace std;   int a[505];   int sorted_a[505];   void rot(int i) {     i--;     int temp = a[i + 2];     a[i + 2] = a[i + 1];     a[i + 1] = a[i];     a[i] = temp;   }   int main() {     ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);     int cases;     cin >> cases;     while (cases--) {       int n;       cin >> n;       for (int i = 0; i < n; i++) {         cin >> a[i];         sorted_a[i] = a[i];       }       sort(sorted_a, sorted_a + n);       vector<int> ans;       for (int i = n - 1; i > 1; i--) {         int j = i;         while (a[j] != sorted_a[i]) j--;         if (j == 0) {           ans.push_back(1);           rot(1);           j++;         }         for (; j < i; j++) {           ans.push_back(j);           rot(j);         }       }       if (a[0] != sorted_a[0]) {         if (a[0] == a[2]) {           ans.push_back(1);           ans.push_back(1);           rot(1);           rot(1);         } else {           for (int i = 2; i < n - 1; i++) {             if (a[i] == a[i + 1]) {               for (int j = i; j >= 1; j--) {                 ans.push_back(j);                 rot(j);               }               break;             }           }         }       }       if (a[0] == sorted_a[0]) {         cout << ans.size() <<   n ;         for (int i : ans) cout << i <<    ;         cout <<   n ;       } else         cout <<  -1 n ;     }     return 0;   }   