#coding:utf-8

def main():

	S=raw_input()

	if not S:
		return 1

	cnt=0
	if S[0]=='R':
		cnt+=3
	else:
		cnt+=2
	

	for i in S[1:]:
		if i=='R':
			cnt=(cnt*2)+1
		else:
			cnt=cnt*2

	return cnt
	
if __name__=='__main__':
	print main()