/in/foo.cc:5:16: error: 'deep' has not been declared
    5 | void dfs(int u,deep){
      |                ^~~~
/in/foo.cc: In function 'void dfs(int, int)':
/in/foo.cc:7:23: error: 'deep' was not declared in this scope
    7 |         maxd=max(maxd,deep);
      |                       ^~~~