#include <bits/stdc++.h>
using i64 = std::int_fast64_t;

constexpr int MOD = 998244353;

i64 powmod(i64 x, i64 n) {
	i64 ret = 1;
	while(n) {
		if(n & 1) (ret *= x) %= MOD;
		(x *= x) %= MOD;
		n >>= 1;
	}
	return ret;
}

int main() {
	i64 n, k; scanf("%lld%lld", &n, &k);

	// 線形篩
	std::vector<int> primes, minp(k + 1, -1);
	for(int i = 2; i < minp.size(); i++) {
		if(minp[i] == -1) {
			minp[i] = i;
			primes.push_back(i);
		}

		for(int p: primes) {
			if(p * i >= minp.size() or p > minp[i]) break;

			minp[p * i] = p;
		}
	}

	// べき乗列挙
	std::vector<i64> powers(k + 1); powers[1] = 1;
	for(int p: primes) powers[p] = powmod(p, n - 1);
	for(int i = 4; i < powers.size(); i++) {
		if(minp[i] == i) continue;
		powers[i] = powers[i / minp[i]] * powers[minp[i]] % MOD;
	}

	auto f = [&](i64 x) -> i64 {
		const i64 A = powers[k] * k % MOD;
		const i64 B = n * x % MOD * powers[k - x] % MOD;
		const i64 C = powers[k - x] * (k - x) % MOD;
		return ((A - B - C) % MOD + MOD) % MOD;
	};

	i64 ans = 0;
	for(int i = 1; i <= k; i++) {
		i64 count = f(i) - f(i - 1);
		count = (count % MOD + MOD) % MOD;
		ans = (ans + count * (k - i + 1) % MOD) % MOD;
	}
	printf("%lld\n", ans);
}