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

const int md = 998244353;

inline int mul(int x, int y) {
	return 1ull * x * y % md;
}

inline int fpow(int x, int y) {
	int ans = 1;
	while (y) {
		if (y & 1) ans = mul(ans, x);
		y >>= 1; x = mul(x, x);
	}
	return ans;
}

const int N = 2005;

vector <int> vec[N];
int l[N], r[N], b[N], mxr[N], mnr[N];
int T, n, m, ans1, ans2;

int main() {
	scanf("%d", &T);
	while (T--) {
		memset(mxr, 0, sizeof(mxr));
		memset(mnr, 0x3f, sizeof(mnr));
		scanf("%d%d", &n, &m);
		for (int i = 1; i <= m; i++) {
			scanf("%d%d", &l[i], &r[i]);
			b[i] = l[i];
			vec[i].clear();
		}
		sort(b + 1, b + m + 1);
		for (int i = 1; i <= m; i++) {
			l[i] = lower_bound(b + 1, b + m + 1, l[i]) - b;
			r[i] = upper_bound(b + 1, b + m + 1, r[i]) - b - 1;
			vec[l[i]].push_back(r[i]);
		}
		for (int i = 1; i <= m; i++) {
			mxr[i] = mxr[i - 1];
			for (auto j : vec[i]) mxr[i] = max(mxr[i], j);
		}
		for (int i = m; i >= 1; i--) {
			mnr[i] = mnr[i + 1];
			for (auto j : vec[i]) mnr[i] = min(mnr[i], j);
		}
		ans1 = ans2 = 1;
		for (int i = 1; i <= m; i++) {
			// l[i], r[i]
			int now1 = l[i] - 1, now2 = r[i], cnt1 = 0, cnt2 = 1;
			while (1) {
				while (now1 < now2) {
					if (mxr[now1 + 1] > now1) {
						++cnt1;
						now1 = mxr[now1 + 1];
					} else break;
				}
				if (now1 < now2) break;
				if (cnt2 * ans2 > cnt1 * ans1) {
					ans1 = cnt2;
					ans2 = cnt1;
				}
				if (mnr[now2 + 1] == 0x3f3f3f3f) break;
				now2 = mnr[now2 + 1]; ++cnt2;
			}
		}
		int ans = mul(ans1, fpow(ans2, md - 2));
		printf("%d\n", ans);
	}
	return 0;
}