/in/foo.cc: In function 'int bfs_1(int)':
/in/foo.cc:31:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i=1;i<a[now].size();i++)
                      ~^~~~~~~~~~~~~~
/in/foo.cc:32:16: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses]
             if (del[a[now][i]]==0)
                ^