foo.cc: In function 'void DFS(int&, int, int)':
foo.cc:30:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < cake.size(); i++)
                   ~~^~~~~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:77:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int rr = 0; rr < mouth.size(); rr++)
                   ~~~^~~~~~~~~~~~~~
foo.cc:74:6: warning: unused variable 'max' [-Wunused-variable]
  int max = 0;
      ^~~