/in/foo.cc: In function 'void DFS1(int)':
/in/foo.cc:15:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int k=0;k<g[i].size();k++){
              ~^~~~~~~~~~~~
/in/foo.cc: In function 'void DFS2(int)':
/in/foo.cc:29:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int k=0;k<g[i].size();k++){
              ~^~~~~~~~~~~~