#include<iostream>
#include<vector>
#include<atcoder/all>

using namespace atcoder;
using namespace std;

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

    long long N, M, L, R;
    while( T-- > 0 )
    {
        cin >> N >> M >> L >> R;
        modint998244353 ans = 0;
        ans = R - L + ( long long )1;
        M /= ( N - 1 ), M++, M %= 998244353;
        ans *= M;

        cout << ans.val() << endl;
    }

    return 0;
}