/in/foo.cc: In function 'int dfs(int)':
/in/foo.cc:20:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (i=0;i<a[x].size();i++)
           ~^~~~~~~~~~~~
/in/foo.cc:17:8: warning: unused variable 'j' [-Wunused-variable]
  int i,j,minn=9876543,maxx=0,xd,cnt=0;
        ^