n,k = map(int,input().split())
N = 1<<n
dp0 = [[0]*n for _ in range(N)]
dp1 = [[0]*n for _ in range(N)]
dp0[1<<(k-1)][k-1] = 1
for mask in range(1<<n):
    for i in range(n):
        if dp0[mask][i] == dp1[mask][i] == 0: continue
        for j in range(n):
            if mask>>j&1: continue
            if i < j:
                dp0[mask|(1<<j)][j] += dp0[mask][i]
                dp1[mask|(1<<j)][j] += dp1[mask][i]
            else:
                dp1[mask|(1<<j)][j] += dp0[mask][i]
print(sum(dp1[N-1]))