answer.code: In function ‘void dfs(int)’:
answer.code:33:15: warning: structured bindings only available with ‘-std=c++17’ or ‘-std=gnu++17’ [-Wc++17-extensions]
   33 |     for (auto [c, _] : gr[v]) {
      |               ^
answer.code: In function ‘void dfs1(int)’:
answer.code:43:15: warning: structured bindings only available with ‘-std=c++17’ or ‘-std=gnu++17’ [-Wc++17-extensions]
   43 |     for (auto [c, _] : g[v]) {
      |               ^
answer.code: In function ‘bool dfs2(int)’:
answer.code:51:15: warning: structured bindings only available with ‘-std=c++17’ or ‘-std=gnu++17’ [-Wc++17-extensions]
   51 |     for (auto [c, cost] : g[v]) {
      |               ^
answer.code: In function ‘int main()’:
answer.code:104:34: error: ‘v’ was not declared in this scope
  104 |         for (auto v : comp[group[v]]) {
      |                                  ^
answer.code:106:27: error: ‘c’ was not declared in this scope
  106 |             if (res[group[c]]) {
      |                           ^