/in/foo.cc: In function 'void dfs(long long int)':
/in/foo.cc:7:14: error: 'step' was not declared in this scope; did you mean 'strsep'?
    7 |         f[u]=step;
      |              ^~~~
      |              strsep
At global scope:
cc1plus: error: '::main' must return 'int'
/in/foo.cc: In function 'int main()':
/in/foo.cc:19:12: error: too many arguments to function 'void dfs(long long int)'
   19 |         dfs(1,0);
      |         ~~~^~~~~
/in/foo.cc:6:6: note: declared here
    6 | void dfs(int u){
      |      ^~~