/in/foo.cc: In function 'void wid(int, int)':
/in/foo.cc:14:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<s[x].son.size();i++)
              ~^~~~~~~~~~~~~~~~
/in/foo.cc: In function 'void dfs(int)':
/in/foo.cc:21:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<s[x].son.size();i++)
              ~^~~~~~~~~~~~~~~~
/in/foo.cc:29:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<s[x].son.size();i++)
              ~^~~~~~~~~~~~~~~~
/in/foo.cc:36:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<s[x].son.size();i++)
              ~^~~~~~~~~~~~~~~~
/in/foo.cc:43:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for(int p=0;p<s[x].son.size();p++)
                ~^~~~~~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:60:16: warning: unused variable 'p' [-Wunused-variable]
  for(int i=1,x,p,c,y;i<=n;++i)
                ^