78ebf503c6f161f323ebf7934f9c706ef7b212a65a015093f854b2cdcbdef2b647ffa6110331d9a5b957be979cc432a6e7e15c4d4d

w가 열린구간 (a,b)에서 항상 존재한다는데 w는 

- dc official App