#coding: utf-8
##yuki_104
import sys

if raw_input()=='':
 print 1
 sys.exit()

s=[]
s=list(raw_input())
k=len(s)

for i in xrange(len(s)):
 if s[i]=='L': s[i]='0'
 elif s[i]=='R': s[i]='1'

s="".join(s)
n=int(s,2)
res=2**k+n

print res