// naive

#include<bits/stdc++.h>
using namespace std;
#include<atcoder/modint>
typedef atcoder::modint998244353 mint;

mint det(vector<vector<mint>> &a){
	assert(a.size() == a[0].size());
	int n = (int)a.size();
	vector<vector<mint>> b = a;
	int piv = 0;
	mint ret = 1;
	for (int j=0; j<n; j++){
		for (int i=piv; i<n; i++){
			if (b[i][j] != 0){
				swap(b[i], b[piv]);
				if (i != piv) ret = -ret;
				mint ip = b[piv][j].inv();
				for (int l=0; l<n; l++){
					if (l != piv){
						mint tmp = ip * b[l][j];
						for (int k=j; k<n; k++){
							b[l][k] -= tmp * b[piv][k];
						}
					}
				}
				ret *= b[piv][j];
				for (int k=j; k<n; k++){
					b[piv][k] *= ip;
				}
				piv++;
				break;
			}
		}
	}
	for (int i=0; i<n; i++){
		ret *= b[i][i];
	}
	return ret;
}

int main() {
	int k; cin >> k;
	int cnt = 2;
	vector<int> a, b;
	vector<int> s, t;
	for(int i=0; i<k; i++) {
		int n, m; cin >> n >> m;
		a.push_back(0);
		b.push_back(cnt);
		a.push_back(1);
		b.push_back(cnt + 1);
		for (int j=0; j<m; j++) {
			int x, y; cin >> x >> y;
			x--; y--;
			a.push_back(x + cnt);
			b.push_back(y + cnt);
		}
		cnt += n;
	}


	vector mat(cnt-1, vector<mint>(cnt-1));
	for (int i=0; i<(int)a.size(); i++) {
		if (a[i] - 1 >= 0 && b[i] - 1 >= 0) {
			mat[a[i]-1][b[i]-1] -= 1;
			mat[b[i]-1][a[i]-1] -= 1;
		}
		if (a[i] - 1 >= 0) {
			mat[a[i]-1][a[i]-1] += 1;
		}
		if (b[i] - 1 >= 0) {
			mat[b[i]-1][b[i]-1] += 1;
		}
	}

	cout << det(mat).val() << endl;
	
}