# 実験から拡張で通ったが公式解説の2つの数列に分ける方式をやってみる

N, K = map(int, input().split())
count = [0]*N

for bit in range(1<<N):
    if bit == 0 or bit == 2**N-1:
        continue
    
    chosen = []
    unchosen = [a for a in range(N)]
    for shift in range(N):
        if bit>>shift & 1 == 1:
            chosen.append(shift)
            unchosen.remove(shift)
    #print('bit', bin(bit), chosen, unchosen)
    if unchosen[-1] > chosen[0]:
        count[unchosen[0]] += 1
#print(count)
ans = count[K-1]
print(ans)