/in/foo.cc: In function 'int dfs(int, int)':
/in/foo.cc:21:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
/in/foo.cc:20:18: warning: iteration 6 invokes undefined behavior [-Waggressive-loop-optimizations]
   if (ss(h*10+b[k])) dfs(h*10+b[k],j+1);
               ~~~^
/in/foo.cc:19:16: note: within this loop
  for (int k=0;k<=6;k++)
               ~^~~