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

if N == 1 or N > M:
    print(1)
    exit()
if N == M:
    print(2)
    exit()

dp = [0] * (M + 2)
dp[0] = 1

if N == 2:
    for i in range(M + 1):
        dp[i + 1] = dp[i] + dp[i - 1]
else:
    dp[1], dp[2] = 1, 1
    for i in range(3, M + 1):
        dp[i] = dp[i - 1] + dp[i - 3]

print(dp[M])