#include <iostream>
#include <cmath>

using namespace std;
using ll = long long;

const ll MOD = 998244353;

void solve() {
    ll N, M, L, R;
    cin >> N >> M >> L >> R;
    ll ans = (R - L + 1) % MOD;
    ans *= ((M - L) / (N - 1) + 1) % MOD;
    ans %= MOD;
    cout << ans << endl;
}

int main() {
	
	int T;
	cin >> T;

    while(T--) solve();

    return 0;
}