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

const long MOD=998244353L;
long mod(long a){
	return a%MOD;
}
long inverse(long a) {
    long b = MOD, u = 1L, v = 0L;
    while(b){
        long t = a / b;
        a -= t * b; swap(a, b);
        u -= t * v; swap(u, v);
    }
    return (u%MOD + MOD) % MOD;
}
long func(long n,long m,long x){
	return mod((mod(m+1)*mod(x+1)+(n-2))/(n-1));
}

int main(){
	int t;
	cin >> t;
	while(t--){
		long n,m,l,r;
		cin >> n >> m >> l >> r;
		//long ans=(m+1)*(r-l+1)/(n-1);
		long ans=mod(func(n,m,r)-func(n,m,l-1));
		cout << ans << endl;
	}
	return 0;
}