#include <bits/stdc++.h>
#define int long long
using namespace std;

const int N = 5e6 + 10, MOD = 998244353;

int T, n, k, inv[N], pow2[N];

void init() {
    inv[0] = 1;
    pow2[0] = 1;
    for (int i = 1; i < N; i++) {
        inv[i] = inv[i-1] * i % MOD;
        pow2[i] = pow2[i-1] * 2 % MOD;
    }
}

signed main() {
	freopen("love.in", "r", stdin);
	freopen("love.out", "w", stdout);
	ios::sync_with_stdio(0);
	cin.tie(0), cout.tie(0);
    init();
    cin >> T;
    while (T--) {
	    cin >> n >> k;
	    if (n == 2 && k == 0) cout << 16 << "\n";
	    else if (n == k) cout << inv[n] * pow2[n] % MOD << "\n";
	    else cout << 0 << "\n";
	}
    return 0;
}