/in/foo.cc: In function 'double dfs(int, int)':
/in/foo.cc:41:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (i=0;i<pos.size();i++)
              ~^~~~~~~~~~~
/in/foo.cc:43:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
          for (j=i+1;j<=i+6&&j<pos.size();j++)
                             ~^~~~~~~~~~~