/in/foo.cc: In function 'int dfs(int)':
/in/foo.cc:11:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<g[x].size();i++)
              ~^~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:49:7: warning: unused variable 'ans' [-Wunused-variable]
   int ans=dfs(1);
       ^~~