func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     std::cin.tie(0);     std::ios::sync_with_stdio(false);     int t;     cin >> t;     while (t--) {       int n, m, k;       cin >> n >> m >> k;       int nn = n - (n % 2 == 1);       int mm = m - (m % 2 == 1);       long long maxx = (nn / 2) * (mm / 2) * 2;       if (n != nn) {         maxx += m / 2;         if (m / 2 > k || (k - m / 2) % 2 == 1) {           cout <<  NO  << endl;           continue;         }       } else {         if (k % 2 == 1) {           cout <<  NO  << endl;           continue;         }       }       if (maxx < k) {         cout <<  NO  << endl;         continue;       }       vector<vector<char>> l = {{ a ,  b ,  c ,  d }, { x ,  y ,  z ,  w }};       vector<char> let = { m ,  n };       int q = 0;       vector<vector<char>> ans(n, vector<char>(m));       if (n != nn) {         for (int i = 0; i < m; i += 2) {           k--;           ans[n - 1][i] = let[q];           ans[n - 1][i + 1] = let[q];           q = (q + 1) % 2;         }       }       q = 0;       if (m != mm) {         for (int i = 0; i < n; i += 2) {           ans[i][m - 1] = let[q];           ans[i + 1][m - 1] = let[q];           q = (q + 1) % 2;         }       }       q = 0;       for (int i = 0; i < nn; i += 2) {         int f = (i % 4 == 0);         q = 0;         for (int j = 0; j < mm; j += 2) {           if (k > 0) {             ans[i][j] = l[f][q];             ans[i][j + 1] = l[f][q];             q = (q + 1) % 4;             ans[i + 1][j] = l[f][q];             ans[i + 1][j + 1] = l[f][q];             q = (q + 1) % 4;             k -= 2;           } else {             ans[i][j] = l[f][q];             ans[i + 1][j] = l[f][q];             q = (q + 1) % 4;             ans[i][j + 1] = l[f][q];             ans[i + 1][j + 1] = l[f][q];             q = (q + 1) % 4;           }         }       }       cout <<  YES  << endl;       for (int i = int(0); i < int(n); i++) {         for (int j = int(0); j < int(m); j++) cout << ans[i][j];         cout << endl;       }     }   }   