Fibonacci towers

import sys
import math
#import numpy as np

sys.setrecursionlimit(10**6)
input = sys.stdin.readline

mod = 998244353


def fib(a, b):
    fib = []
    for i in range(0, a):
        fib.append(1)
    for i in range(a, b + 1):
        fib.append((fib[-1] + fib[-a]) % mod)
    return fib[b]

def fast_exp(m, n):
    if n == 0:
        return [[int(i == j) for i in range(len(m))] for j in range(len(m))]
    g = [[int(i == j) for i in range(len(m))] for j in range(len(m))]
    while n > 1:
        if n % 2 == 1:
            g = MM(g, m)
            n -= 1
        m = MM(m, m)
        n //= 2
    return MM(g, m)


def MM(x, y):
    c = []
    for i in range(0, len(x)):
        temp = []
        for j in range(0, len(y[0])):
            s = 0
            for k in range(0, len(x[0])):
                s += (x[i][k] * y[k][j]) % mod
            temp.append(s % mod)
        c.append(temp)
    return c


def create_f_m(a):
    m = []
    fr = [0] * a
    fr[0], fr[-1] = 1, 1
    m.append(fr)
    for i in range(a - 1):
        r = [0] * a
        r[i] = 1
        m.append(r)
    return m



a, b = map(int, input().split())
# a = int(input())

if b < a:
    print(1)
else:
    m = create_f_m(a)
    # print(m)
    fb = fast_exp(m, b - a + 1)
    # print(fb)
    print(sum(fb[0]) % mod)
    # print(fib(a, b % mod))

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