def kuzya(D, k):
    A = [1 if j == 0 else '.' for j in range(D + 1)]
    for i in range(1, D + 1):
        if i <= k:
            A[i] = sum(A[0:i])
        else:
            A[i] = sum(A[i - k:i])
    return A[-1]
n, s = list(map(int, input().split()))
print(kuzya(n, s))