/in/foo.cc: In function 'void DFS1(int, int)':
/in/foo.cc:14:18: 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, int)':
/in/foo.cc:25:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int k=0;k<g[i].size();k++){
                 ~^~~~~~~~~~~~