#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define int long long
#define otto auto
const int MAXN=1e6+10;
const int INF=1ll*1e7*1e9;
const int MOD = 998244353;
const int inv = (MOD + 1) / 2;
int T,N,M,K,P,Q;

string str;
int a[MAXN];
int dp[MAXN];

void prepare(){
	scanf("%lld",&N);
	cin>>str;
	dp[0] = 1;
	for(int i = 1;i <= 2 * N; i++){
		char c = str[i-1];
		if(a[i-1] == 0){
			dp[i] = dp[i-1];
		}
		else if(a[i-1] == 1){
			if(c == 'B') dp[i] = dp[i-1] * 2 % MOD;
			else dp[i] = dp[i-1];
		}
		else if(a[i-1] >= 2){
			if(c == 'B') dp[i] = dp[i-1] * (a[i-1] - 1) % MOD * a[i-1] % MOD;
			else dp[i] = dp[i-1];
		}
		else if(a[i-1] == -1){
			if(c == 'W') dp[i] = dp[i-1] * 2 % MOD;
			else dp[i] = dp[i-1];
		}
		else if(a[i-1] <= -2){
			if(c == 'W') dp[i] = (a[i-1] + 1) * a[i-1] % MOD * dp[i-1] % MOD;
			else dp[i] = dp[i-1];
		}
		if(c == 'W') a[i] = a[i-1] + 1;
		else a[i] = a[i-1] - 1;
	}
	cout<<dp[2*N] * inv %MOD * inv% MOD<<endl;
}

signed main(){
	//ios::sync_with_stdio(0);
	T=1;
	scanf("%lld",&T);
	while(T--){
	    prepare();
	}
	return 0;
}