import sys
readline=sys.stdin.readline

N,K=map(int,readline().split())
K-=1
ans=0
for bit in range(1,(1<<N)-1):
    lstl,lstr=[],[]
    for i in range(N):
        if bit&1<<i:
            lstl.append(i)
        else:
            lstr.append(i)
    if lstl[0]==K and lstl[-1]>lstr[0]:
        ans+=1
print(ans)