answer.code: In function ‘void build_as()’:
answer.code:85:31: error: ‘n’ was not declared in this scope
   85 |                 for(int j=0;j<n;j++){
      |                               ^
answer.code: In function ‘void dfs2(int, int)’:
answer.code:142:28: error: ‘mx’ was not declared in this scope; did you mean ‘ax’?
  142 |                         if(mx==-1 || w[h].sz>w[w[r].mx].sz){
      |                            ^~
      |                            ax
answer.code: In function ‘void go(int, int, int, int)’:
answer.code:160:17: error: ‘ab’ was not declared in this scope; did you mean ‘ax’?
  160 |                 ab=get(r,f);
      |                 ^~
      |                 ax