func_code_string: #include <bits/stdc++.h>   using namespace std;   void change_stream(char* in, char* out) {     ifstream fin;     fin.open(in);     ofstream fout;     fout.open(out);     if (fin && fout) {       freopen(in,  r , stdin);       freopen(out,  w , stdout);     }   }   long long a[500], renum[500];   void shift(long long i) {     long long p = a[i];     a[i] = a[i + 2];     a[i + 2] = a[i + 1];     a[i + 1] = p;     renum[a[i]] = i;     renum[a[i + 1]] = i + 1;     renum[a[i + 2]] = i + 2;   }   void solve() {     long long n;     cin >> n;     pair<long long, long long> s[n];     for (long long i = 0; i < n; i++) {       cin >> a[i];       s[i] = {a[i], i};     }     sort(s, s + n);     for (long long i = 0; i < n; i++) {       renum[i] = s[i].second;       a[renum[i]] = i;     }     long long sdv = 0;     for (long long i = 0; i < n; i++)       for (long long j = i + 1; j < n; j++)         if (a[i] > a[j]) sdv++;     if (sdv % 2) {       bool flag = false;       for (long long i = 0; i < n - 1; i++)         if (s[i].first == s[i + 1].first) {           swap(a[s[i].second], a[s[i + 1].second]);           renum[a[s[i].second]] = s[i].second;           renum[a[s[i + 1].second]] = s[i + 1].second;           flag = true;           break;         }       if (!flag) {         cout <<  -1 n ;         return;       }     }     vector<long long> ans;     for (long long i = n - 1; i > 1; i--) {       while (renum[i] < i) {         long long l = max(0ll, renum[i] - 1);         ans.push_back(l);         shift(l);       }     }     cout << ans.size() <<   n ;     for (long long i : ans) cout << i + 1 <<    ;     cout <<   n ;   }   signed main() {     change_stream( in ,  out );     ios::sync_with_stdio(0);     cin.tie(0);     long long test_count = 1;     cin >> test_count;     while (test_count--) solve();   }   