/in/foo.cc: In function 'int bfs_1(int, int, int*, int*)':
/in/foo.cc:42:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i=0;i<c.size();i++)
                ~^~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:75:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i=0;i<c.size();i++)
                ~^~~~~~~~~
/in/foo.cc:77:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i=0;i<c.size()-1;i++)
                ~^~~~~~~~~~~
/in/foo.cc:81:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i=0;i<c.size();i++)
                ~^~~~~~~~~