#include <bits/stdc++.h>
#define IOS ios::sync_with_stdio(0), cin.tie(0)
#define int long long
#define endl '\n'
#define lowbit(x) (x & -x)
#define all(s) s.begin(), s.end()
#define pii pair<int, int>
#define ls(x) (x << 1)
#define rs(x) (x << 1 | 1)
#define here system("pause")
using namespace std;
template <class T>
inline void read(T &x)
{
	x = 0;
	char c = getchar();
	bool f = 0;
	for (; !isdigit(c); c = getchar())
		f ^= (c == '-');
	for (; isdigit(c); c = getchar())
		x = (x << 3) + (x << 1) + (c ^ 48);
	x = f ? -x : x;
}
template <class T>
inline void write(T x)
{
	if (x < 0)
		putchar('-'), x = -x;
	if (x < 10)
		putchar(x + 48);
	else
		write(x / 10), putchar(x % 10 + 48);
}
template <typename T>
void chkmin(T &lhs, const T &rhs) { lhs = lhs > rhs ? rhs : lhs; }
template <typename T>
void chkmax(T &lhs, const T &rhs) { lhs = lhs < rhs ? rhs : lhs; }

const int N = 2e5 + 5;
const int mod = 998244353;
const int INF = 8e18 + 9;
const double eps = 1e-9;
const double Pi = acos(-1);
inline int pow(int a, int b, int p)
{
	int res = 1 % p;
	while (b)
	{
		if (b & 1)
			res = res * a % p;
		a = a * a % p, b >>= 1;
	}
	return res;
}
inline int inv(int a, int p) { return pow(a, p - 2, p) % p; }
mt19937 rnd(chrono::duration_cast<chrono::nanoseconds>(chrono::system_clock::now().time_since_epoch()).count());
int randint(int L, int R)
{
	uniform_int_distribution<int> dist(L, R);
	return dist(rnd);
}

int n;
int a[N], b[N];
int dp[25][25]; // dp[i][j] 表示前 i 个轮，甲的得分为 j 的方案数
inline void sol()
{
	cin >> n;
	for (int i = 0; i <= min(n + 1, 21LL); i++)
	{
		for (int j = 0; j <= 20; j++)
		{
			dp[i][j] = 0;
		}
	}

	for (int i = 1; i <= n; i++)
	{
		cin >> a[i] >> b[i];
		if (a[i] < b[i])
			swap(a[i], b[i]); // a[i] is bigger
	}

	for (int i = 1; i <= n; i++)
	{
		if (a[i] != -1)
		{
			if (a[i] + b[i] != i)
				return cout << 0 << endl, void();
			if (a[i] >= 11 && a[i] - b[i] >= 2 && i != n)
				return cout << 0 << endl, void();
		}
	}

	if (n < 11)
		return cout << 0 << endl, void();
	if (n > 20 && (n % 2 == 1))
		return cout << 0 << endl, void();
    if (a[n] != -1 && (a[n] < 11 || a[n] - b[n] < 2))
        return cout << 0 << endl, void();

	dp[0][0] = 1;
	for (int i = 1; i <= min(n, 20LL); i++)
	{
		if (a[i] == -1)
		{
			for (int j = 0; j <= i; j++)
			{
				if (j == 0)
					dp[i][j] = (dp[i][j] + dp[i - 1][j]) % mod;
				else
					dp[i][j] = (dp[i][j] + dp[i - 1][j] + dp[i - 1][j - 1]) % mod;
				if (max(j, i - j) >= 11 && max(j, i - j) - min(j, i - j) >= 2 && i != n)
					dp[i][j] = 0;
			}
		}
		else
		{
			if (a[i] == 0)
				dp[i][a[i]] = (dp[i][a[i]] + dp[i - 1][a[i]]) % mod;
			else
				dp[i][a[i]] = (dp[i][a[i]] + dp[i - 1][a[i]] + dp[i - 1][a[i] - 1]) % mod;
			if (max(a[i], i - a[i]) >= 11 && max(a[i], i - a[i]) - min(a[i], i - a[i]) >= 2 && i != n)
				dp[i][a[i]] = 0;

			if (a[i] == b[i])
				continue;

			if (b[i] == 0)
				dp[i][b[i]] = (dp[i][b[i]] + dp[i - 1][b[i]]) % mod;
			else
				dp[i][b[i]] = (dp[i][b[i]] + dp[i - 1][b[i]] + dp[i - 1][b[i] - 1]) % mod;
			if (max(b[i], i - b[i]) >= 11 && max(b[i], i - b[i]) - min(b[i], i - b[i]) >= 2 && i != n)
				dp[i][b[i]] = 0;
		}
	}

	int ans = 0;
	if (n > 20)
	{
		ans = dp[20][10];
		for (int i = 22; i <= n; i += 2)
		{
			if (a[i] != b[i] && i != n)
				return cout << 0 << endl, void();
			ans = ans * 2 % mod;
		}
	}
	else
	{
		ans = (dp[n][n - 11] + dp[n][11]) % mod;
	}
	cout << ans << endl;
}
signed main()
{
	IOS;
	int tc = 1;
	cin >> tc;
	while (tc--)
	{
		sol();
	}
	return 0;
}