#include "bits/stdc++.h"
using namespace std;
#ifdef _DEBUG
#include "dump.hpp"
#else
#define dump(...)
#endif

//#define int long long
#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define rrep(i,a,b) for(int i=(b)-1;i>=(a);i--)
#define all(c) begin(c),end(c)
const int INF = sizeof(int) == sizeof(long long) ? 0x3f3f3f3f3f3f3f3fLL : 0x3f3f3f3f;
const int MOD = (int)(1e9) + 7;
template<class T> bool chmax(T &a, const T &b) { if (a < b) { a = b; return true; } return false; }
template<class T> bool chmin(T &a, const T &b) { if (a > b) { a = b; return true; } return false; }

template <int MOD> struct ModInt {
	static const int Mod = MOD;
	unsigned x;
	ModInt() : x(0) {}
	ModInt(signed sig) {
		int sigt = sig % MOD;
		if (sigt < 0)
			sigt += MOD;
		x = sigt;
	}
	ModInt(signed long long sig) {
		int sigt = sig % MOD;
		if (sigt < 0)
			sigt += MOD;
		x = sigt;
	}
	int get() const { return (int)x; }

	ModInt &operator+=(ModInt that) {
		if ((x += that.x) >= MOD)
			x -= MOD;
		return *this;
	}
	ModInt &operator-=(ModInt that) {
		if ((x += MOD - that.x) >= MOD)
			x -= MOD;
		return *this;
	}
	ModInt &operator*=(ModInt that) {
		x = (unsigned long long)x * that.x % MOD;
		return *this;
	}
	ModInt &operator/=(ModInt that) { return *this *= that.inverse(); }

	ModInt operator+(ModInt that) const { return ModInt(*this) += that; }
	ModInt operator-(ModInt that) const { return ModInt(*this) -= that; }
	ModInt operator*(ModInt that) const { return ModInt(*this) *= that; }
	ModInt operator/(ModInt that) const { return ModInt(*this) /= that; }

	ModInt inverse() const {
		signed a = x, b = MOD, u = 1, v = 0;
		while (b) {
			signed t = a / b;
			a -= t * b;
			std::swap(a, b);
			u -= t * v;
			std::swap(u, v);
		}
		if (u < 0)
			u += MOD;
		ModInt res;
		res.x = (unsigned)u;
		return res;
	}
};
template <int MOD> ostream &operator<<(ostream &os, const ModInt<MOD> &m) {
	return os << m.x;
}
template <int MOD> istream &operator >> (istream &is, ModInt<MOD> &m) {
	signed long long s;
	is >> s;
	m = ModInt<MOD>(s);
	return is;
};
// pow(mint(2), 1000) のように
template <int MOD> ModInt<MOD> pow(ModInt<MOD> a, unsigned long long k) {
	ModInt<MOD> r = 1;
	while (k) {
		if (k & 1)
			r *= a;
		a *= a;
		k >>= 1;
	}
	return r;
}

//#define int long long を使っても大丈夫
using mint = ModInt<1000000007>;


// nCrで用いる
vector<mint> fact, factinv;
// nCrで用いる 予め計算しておく
void nCr_compute_factinv(int N) {
	N = min(N, mint::Mod - 1);
	fact.resize(N + 1);
	factinv.resize(N + 1);
	fact[0] = 1;
	rep(i, 1, N + 1) fact[i] = fact[i - 1] * i;
	factinv[N] = fact[N].inverse();
	for (int i = N; i >= 1; i--)
		factinv[i - 1] = factinv[i] * i;
}
mint nCr(int n, int r) {
	if (n >= mint::Mod)
		return nCr(n % mint::Mod, r % mint::Mod) *
		nCr(n / mint::Mod, r / mint::Mod);
	return r > n ? 0 : fact[n] * factinv[n - r] * factinv[r];
}

mint nHr(int n, int r) { return r == 0 ? 1 : nCr(n + r - 1, r); }
signed main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

	int N; cin >> N;
	nCr_compute_factinv(N);
	string S;
	cin >> S;

	mint ans;
	if (S.front() == 'B' and S.back() == 'B') {
		ans = 1;
	}
	else {
		ans = 0;
	}

	int s = 0;
	rep(i, 0, S.size()) {
		int b = (S[i] == 'B');

		int d = (b + s) % 2;
		dump(S[i], b, d, s);
		if (d == 1) {
			s++;
		}
		else {
			ans *= s;
			s--;
		}
		dump(ans, s);
	}
	dump(s);
	if (s != 0) {
		ans = 0;
	}

	dump(ans);

	cout << ans * fact[N] << endl;


	return 0;
}

Measured memory_bytes: 1488