answer.code: In function ‘void dd(int, int)’:
answer.code:36:19: warning: structured bindings only available with ‘-std=c++17’ or ‘-std=gnu++17’
   36 |         for (auto [i, j]: v[x])
      |                   ^
answer.code: In function ‘void dfs(int, int, int, int, int)’:
answer.code:58:19: warning: structured bindings only available with ‘-std=c++17’ or ‘-std=gnu++17’
   58 |         for (auto [i, j]: v[x])
      |                   ^
answer.code: In function ‘void dfs2(int, int)’:
answer.code:80:19: warning: structured bindings only available with ‘-std=c++17’ or ‘-std=gnu++17’
   80 |         for (auto [i, j]: v[x])
      |                   ^
answer.code:86:43: warning: structured bindings only available with ‘-std=c++17’ or ‘-std=gnu++17’
   86 |                                 for (auto [p, q]: pb[i]) pb[x][p] += q;
      |                                           ^
answer.code:88:43: warning: structured bindings only available with ‘-std=c++17’ or ‘-std=gnu++17’
   88 |                                 for (auto [p, q]: pc[i]) pc[x][p] += q;
      |                                           ^
answer.code: In function ‘void pre()’:
answer.code:176:31: error: too few arguments to function ‘bool zz(int)’
  176 |                         if (zz()) {
      |                             ~~^~
answer.code:129:6: note: declared here
  129 | bool zz(int rt) {
      |      ^~
answer.code: In function ‘bool zz(int)’:
answer.code:142:1: warning: control reaches end of non-void function [-Wreturn-type]
  142 | }
      | ^