answer.code: In function ‘std::pair<int, int> middle(int, int, int, int)’:
answer.code:25:20: error: missing template arguments before ‘(’ token
   25 |         return pair((a+c)/2, (b+d)/2);
      |                    ^
answer.code: In function ‘void test_case()’:
answer.code:32:20: warning: structured bindings only available with ‘-std=c++17’ or ‘-std=gnu++17’
   32 |         for (auto &[a, b] : pieces) {
      |                    ^
answer.code:68:19: warning: structured bindings only available with ‘-std=c++17’ or ‘-std=gnu++17’
   68 |         for (auto [a, b] : pieces) {
      |                   ^
answer.code:70:50: error: missing template arguments before ‘(’ token
   70 |                 vector<vector<int>> vis(N, vector(N, 0)); vis[a][b] = true;
      |                                                  ^
answer.code:73:30: warning: structured bindings only available with ‘-std=c++17’ or ‘-std=gnu++17’
   73 |                         auto [i, j] = q.front(); q.pop();
      |                              ^
answer.code:76:38: warning: structured bindings only available with ‘-std=c++17’ or ‘-std=gnu++17’
   76 |                                 auto [k, l] = pair(p/N, p%N);
      |                                      ^
answer.code:76:51: error: missing template arguments before ‘(’ token
   76 |                                 auto [k, l] = pair(p/N, p%N);
      |                                                   ^
answer.code:77:63: error: missing template arguments before ‘(’ token
   77 |                                 if (middle(i, j, k, l) == pair(a, b)) continue;
      |                                                               ^