#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
#define rep(i, n) for(int i=0;i<(n);++i)
#define rep1(i, n) for(int i=1;i<=(n);i++)
#define ll long long
using mint = modint998244353;
using P = pair<ll,ll>;
using lb = long double;
using T = tuple<ll, ll, ll>;
#ifdef LOCAL
#  include <debug_print.hpp>
#  define dbg(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define dbg(...) (static_cast<void>(0))
#endif

int main()
{
    int t;
    cin >> t;
    rep(_,t){
        ll n, m, l, r;
        cin >> n >> m >> l >> r;
        mint ans = 0;
        {
            ll high = r/(n-1);
            ll low = (l-1)/(n-1);
            ans += mint(high)*mint(r) - mint(high)*mint(l) - mint(n-1)*mint(high)*mint(high-1)*mint(2).inv() + mint(high);
            ans += mint(low)*mint(r-l+1);
        }
        r = m-l;
        l = m-r;
        {
            ll high = r/(n-1);
            ll low = (l-1)/(n-1);
            ans += mint(high)*mint(r) - mint(high)*mint(l) - mint(n-1)*mint(high)*mint(high-1)*mint(2).inv() + mint(high);
            ans += mint(low)*mint(r-l+1);
        }
        ans += r-l+1;
        cout << ans.val() << "\n";
    }   
    return 0;
}