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

using ll = long long;
#define int long long

// [a -> b-1]
#define reps(i, a, b) for (int i = (int)(a); i < (int)(b); i++)
// [0 -> a-1]
#define rep(i, a) reps(i, 0, (a))
// [a-1 -> b]
#define rreps(i, a, b) for (int i = (int)((a)-1); i >= (int)(b); i--)
// [a-1 -> 0]
#define rrep(i, a) rreps(i, a, 0)
#define all(v) (v).begin(), (v).end()
// next_permutation(all(v))
#define PERM(v) next_permutation(all(v))
/*sort(all(v));
 * (v).erase(unique(all(v)), v.end())*/
#define UNIQUE(v)\
	sort(all(v));\
	(v).erase(unique(all(v)), v.end())
#define MINV(v) min_element(all(v))
#define MAXV(v) max_element(all(v))
#define MIN3(a, b, c) min(min(a, b), c)
#define MIN4(a, b, c, d) min(MIN3(a, b, c), d)
#define MIN5(a, b, c, d, e) min(MIN4(a, b, c, d), e)
#define MIN6(a, b, c, d, e, f) min(MIN5(a, b, c, d, e), f)
#define MAX3(a, b, c) max(max(a, b), c)
#define MAX4(a, b, c, d) max(MAX3(a, b, c), d)
#define MAX5(a, b, c, d, e) max(MAX4(a, b, c, d), e)
#define MAX6(a, b, c, d, e, f) max(MAX5(a, b, c, d, e), f)
// b is [a, c)
#define RANGE(a, b, c) ((a) <= (b) && (b) < (c))
// c is [a, e) && d is [b, f)
#define RANGE2D(a, b, c, d, e, f) (RANGE((a), (c), (e)) && RANGE((b), (d), (f)))
#define chmin(a, b) a = min(a, (b))
#define chmin3(a, b, c) a = MIN3(a, (b), (c))
#define chmin4(a, b, c, d) a = MIN4(a, (b), (c), (d))
#define chmin5(a, b, c, d, e) a = MIN5(a, (b), (c), (d), (e))
#define chmin6(a, b, c, d, e, f) a = MIN6(a, (b), (c), (d), (e), (f))
#define chmax(a, b) a = max(a, (b))
#define chmax3(a, b, c) a = MAX3(a, (b), (c))
#define chmax4(a, b, c, d) a = MAX4(a, (b), (c), (d))
#define chmax5(a, b, c, d, e) a = MAX5(a, (b), (c), (d), (e))
#define chmax6(a, b, c, d, e, f) a = MAX6(a, (b), (c), (d), (e), (f))
#define fcout cout << fixed << setprecision(15)
#define YES(f) cout << ((f) ? YES_STR : NO_STR) << endl;

const long long MOD = 1000000007;

namespace mylib {
template<int mod>
struct ModInt {
	using ll = long long;
	int x;
	const static int M = mod;
	ModInt(ll x_) {
		x = x_ % mod;
		if (x < 0) x += mod;
	}
	ModInt() : ModInt(0) {}
	inline ModInt& operator+=(const ModInt rhs) {
		x += rhs.x;
		x %= mod;
		return (*this);
	}
	inline ModInt& operator-=(const ModInt rhs) {
		x += -rhs.x;
		return *this;
	}
	inline ModInt& operator*=(const ModInt rhs) {
		x = ((ll) x * rhs.x) % mod;
		return *this;
	}
	inline ModInt& operator/=(ModInt rhs) {
		return *this *= rhs.power(mod - 2);
	}
	inline ModInt power(ll p) {
		ModInt res = 1;
		ModInt a = x;
		for (; p; res = p & 1 ? res * a : res, a *= a, p >>= 1);
		return res;
	}
	inline ModInt& operator=(const ModInt& rhs) {
		this->x = rhs.x;
		return *this;
	}
	inline int operator==(const ModInt& rhs) const {
		return this->x == rhs.x;
	}
	inline int operator!=(const ModInt& rhs) const {
		return !(*this != rhs);
	}
	inline ModInt operator++(signed unused) {
		ModInt res(*this);
		++(*this);
		return res;
	}
	inline ModInt& operator++() {
		(*this) += 1;
		return (*this);
	}
	inline ModInt operator--(signed unused) {
		ModInt res(*this);
		--(*this);
		return res;
	}
	inline ModInt& operator--() {
		(*this) -= 1;
		return (*this);
	}
	inline ModInt operator+() const {
		return (*this);
	}
	inline ModInt operator-() const {
		return (*this).x ? ModInt(mod - (*this).x) : ModInt(0);
	}
	friend const ModInt operator+(const ModInt& lhs, const ModInt& rhs) {return ModInt(lhs) += rhs;}
	friend const ModInt operator-(const ModInt& lhs, const ModInt& rhs) {return ModInt(lhs) -= rhs;}
	friend const ModInt operator*(const ModInt& lhs, const ModInt& rhs) {return ModInt(lhs) *= rhs;}
	friend const ModInt operator/(const ModInt& lhs, const ModInt& rhs) {return ModInt(lhs) /= rhs;}
	explicit operator int() const {return x;}
	friend ostream& operator<<(ostream& lhs, const ModInt& rhs) {
		lhs << rhs.x;
		return lhs;
	}
	friend istream& operator>>(istream& lhs, ModInt& rhs) {
		long long t;
		lhs >> t;
		rhs = ModInt(t);
		return lhs;
	}
};
using modint = ModInt<1000000007>;
//using modint = ModInt<998244353>;
modint operator"" _mi(unsigned long long lit) {
	return modint(lit % modint::M);
}
}; // mylib
using namespace mylib;

modint solve(long long N, std::string S) {
	vector<bool> x(2 * N);
	rep(i, 2*N) {
		x[i] = (S[i] == 'B');
	}
	modint res = 1;
	int l = 0;
	bool f = false;
	rep(i, 2*N) {
		if (f ^ x[i]) {
			l++;
		} else {
			if (l == 0) return 0;
			res *= l;
			l--;
		}
		f = !f;
	}
	if (l != 0) {
		return 0;
	}
	reps(i, 1, N+1) {
		res *= i;
	}
	return res;
}

signed main() {
	long long N;
	scanf("%lld",&N);
	std::string S;
	std::cin >> S;
	cout << solve(N, S) << endl;
	return 0;
}


Measured memory_bytes: 772