/in/foo.cc: In function 'bool isok(int)':
/in/foo.cc:19:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<ct.size();i++){
                 ~^~~~~~~~~~
/in/foo.cc: In function 'void bfs()':
/in/foo.cc:32:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int i=0;i<plans.size();i++){
                     ~^~~~~~~~~~~~~