// #include <bits/stdc++.h>
#include <iostream>
using namespace std;
using ll = long long;
ll const m = 998244353;
void solve() {
	int N, M;
	cin >> N >> M;
	if (N < 4) {
		ll ans[] = {1ll, (ll)N};
		while (--M) {
            // cout << (ans[0] + ans[1]) % m << endl;
			ll a2[2];
			a2[0] = ans[0] + ans[1];
			a2[1] = ans[0] * N + ans[1] * (N - 1);
			ans[0] = a2[0] % m; ans[1] = a2[1] % m;
		}
		cout << (ans[0] + ans[1]) % m << endl;
	} else {
		// swap(N, M);
		ll ans[3];
		ans[0] = 1;
		ans[1] = N;
		ans[2] = N;
		ans[2] *= (N - 3);
		ans[2] /= 2;
		ans[2] %= m;
		ll X[3];
		X[0] = ans[2];
		X[1] = N - 2;
		X[1] = (X[1] * (N - 3)) / 2;
		X[2] = N - 2;
		X[2] = (X[2] * (N - 3)) / 2 - (N - 4);
		X[1] %= m; X[2] %= m;
		while (--M) {
			 ll a2[3];
			 a2[0] = ans[0] + ans[1] + ans[2];
			 a2[1] = ans[0] * N + ans[1] * (N - 1) + ans[2] * (N - 2);
			 a2[2] = ans[0] * X[0] + ans[1] * X[1] + ans[2] * X[2];
			 for (int i = 0; i < 3; i ++) ans[i] = a2[i] % m;
		}
		cout << (ans[0] + ans[1] + ans[2]) % m << endl;
	}
}
int main () {
	int T;
	cin >> T;
	while (T--) {
		solve();
	}
}