/in/foo.cc: In function 'void dfs(int, ULL)':
/in/foo.cc:16:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     if(d==n+1){
        ~^~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:34:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int i=1; i<=n; i++) num[i] = read();
                      ~^~~