/in/foo.cc: In function 'int main()':
/in/foo.cc:88:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int j=0;j<room_link[i].size();j++){
                 ~^~~~~~~~~~~~~~~~~~~~
/in/foo.cc: In function 'bool GoN(int)':
/in/foo.cc:63:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^