/in/foo.cc: In function 'double prim(int)':
/in/foo.cc:34:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<poi[src].size();i++)
              ~^~~~~~~~~~~~~~~~
/in/foo.cc:47:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for(int i=0;i<poi[now.to].size();i++)
                ~^~~~~~~~~~~~~~~~~~~