/in/foo.cc: In function 'void DFS(int)':
/in/foo.cc:27:15: 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 DFSr(int)':
/in/foo.cc:36:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int k=0;k<gr[i].size();k++){
              ~^~~~~~~~~~~~~

FileNotFoundError('input/input1.txt',)