N,K=map(int,input().split())

DP=[[[0]*(1<<N) for j in range(N)]for i in range(2)]
DP[0][K-1][1<<(K-1)]=1


for i in range(1<<N):
    for j in range(N):
        if DP[0][j][i]!=0:
            for k in range(N):
                if i & (1<<k) == 0:
                    if k>j:
                        DP[0][k][i|(1<<k)]+=DP[0][j][i]
                    else:
                        DP[1][k][i|(1<<k)]+=DP[0][j][i]
        if DP[1][j][i]!=0:
            for k in range(N):
                if i & (1<<k) == 0:
                    if k>j:
                        DP[1][k][i|(1<<k)]+=DP[1][j][i]

ANS=0
for i in range(N):
    ANS+=DP[1][i][-1]

print(ANS)