/in/foo.cc: In function 'void dp(int, int)':
/in/foo.cc:10:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<to[x].size();++i) {
              ~^~~~~~~~~~~~~
/in/foo.cc: In function 'void dfs(int, int)':
/in/foo.cc:21:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<to[x].size();++i) {
              ~^~~~~~~~~~~~~