#include <iostream>
#include <cstring>
#include <algorithm>
#include <vector>

#define x first
#define y second

using namespace std;

typedef long long LL;
typedef pair<int, int> PII;

const int N = 500010, P = 998244353;

int n, m;
PII d[N];
int tr[N << 1];
vector<int> g;

bool cmp(PII a, PII b)
{
    return a.y < b.y;
}

int lowbit(int x)
{
    return x & -x;
}

void update(int x, int c)
{
    for (int i = x; i <= n; i += lowbit(i)) tr[i] += c;
}

int query(int x)
{
    int res = 0;
    for (int i = x; i; i -= lowbit(i)) res += tr[i];
    return res;
}

int find(int x)
{
    return lower_bound(g.begin(), g.end(), x) - g.begin() + 1;
}

int main()
{
    int T;
    cin >> T;
    while (T -- )
    {
        g.clear();
        scanf("%d%d", &n, &m);
        for (int i = 1; i <= n; i ++ )
        {
            scanf("%d%d", &d[i].x, &d[i].y);
            g.push_back(d[i].x), g.push_back(d[i].y);
        }

        sort(d + 1, d + n + 1, cmp);
        sort(g.begin(), g.end());
        g.erase(unique(g.begin(), g.end()), g.end());

        LL res = 1;
        for (int i = n; i; i -- )
        {
            d[i].x = find(d[i].x), d[i].y = find(d[i].y);
            res = res * max(0, m - query(d[i].y)) % P;
            update(d[i].x, 1);
        }
        for (int i = 1; i <= n; i ++ ) update(d[i].x, -1);
        printf("%lld\n", res);
    }

    return 0;
}

/*

2
4 3
4 7
3 4
5 8
1 3
2 1000
100 200
300 400

*/