/in/foo.cc: In function 'int dfs(int, int, int)':
/in/foo.cc:21:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:26:6: warning: unused variable 'dx' [-Wunused-variable]
  int dx[10000];
      ^~
/in/foo.cc:31:2: warning: 'i' may be used uninitialized in this function [-Wmaybe-uninitialized]
  for(int i;i<=n;i++)
  ^~~