mod = 998244353


def main():
    import sys
    input = sys.stdin.readline

    N = int(input())
    M = int(input())

    ans = (pow(2, N, mod) - 1) % mod
    c = 1
    for i in range(1, M):
        c *= N + 1 - i
        c *= pow(i, mod - 2, mod)
        c %= mod
        ans = (ans - c) % mod
    print(ans)


if __name__ == '__main__':
    main()