/in/foo.cc: In function 'void spfa1()':
/in/foo.cc:24:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i=0;i<cn[x].size();i++)
                ~^~~~~~~~~~~~~
/in/foo.cc: In function 'void spfa2()':
/in/foo.cc:52:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i=0;i<ccn[x].size();i++)
                ~^~~~~~~~~~~~~~