#include "bits/stdc++.h"
#include<unordered_map>
#include<unordered_set>
#pragma warning(disable:4996)
using namespace std;
using ld = long double;
template<class T>
using Table = vector<vector<T>>;


const int mod = 1000000007;
struct Mod {
public:
	int num;
	Mod() : Mod(0) { ; }
	Mod(long long int n) : num((n % mod + mod) % mod) {
		static_assert(mod<INT_MAX / 2, "mod is too big, please make num 'long long int' from 'int'");
	}
	Mod(int n) : Mod(static_cast<long long int>(n)) { ; }
	operator int() { return num; }
};

Mod operator+(const Mod a, const Mod b) { return Mod((a.num + b.num) % mod); }
Mod operator+(const long long int a, const Mod b) { return Mod(a) + b; }
Mod operator+(const Mod a, const long long int  b) { return b + a; }
Mod operator++(Mod &a) { return a + Mod(1); }
Mod operator-(const Mod a, const Mod b) { return Mod((mod + a.num - b.num) % mod); }
Mod operator-(const long long int a, const Mod b) { return Mod(a) - b; }
Mod operator--(Mod &a) { return a - Mod(1); }
Mod operator*(const Mod a, const Mod b) { return Mod(((long long)a.num * b.num) % mod); }
Mod operator*(const long long int a, const Mod b) { return Mod(a)*b; }
Mod operator*(const Mod a, const long long int b) { return Mod(b)*a; }
Mod operator*(const Mod a, const int b) { return Mod(b)*a; }
Mod operator+=(Mod &a, const Mod b) { return a = a + b; }
Mod operator+=(long long int &a, const Mod b) { return a = a + b; }
Mod operator-=(Mod &a, const Mod b) { return a = a - b; }
Mod operator-=(long long int &a, const Mod b) { return a = a - b; }
Mod operator*=(Mod &a, const Mod b) { return a = a * b; }
Mod operator*=(long long int &a, const Mod b) { return a = a * b; }
Mod operator*=(Mod& a, const long long int &b) { return a = a * b; }
Mod operator^(const Mod a, const int n) {
	if (n == 0) return Mod(1);
	Mod res = (a * a) ^ (n / 2);
	if (n % 2) res = res * a;
	return res;
}
Mod mod_pow(const Mod a, const int n) {
	if (n == 0) return Mod(1);
	Mod res = mod_pow((a * a), (n / 2));
	if (n % 2) res = res * a;
	return res;
}
Mod inv(const Mod a) { return a ^ (mod - 2); }
Mod operator/(const Mod a, const Mod b) {
	assert(b.num != 0);
	return a * inv(b);
}
Mod operator/(const long long int a, const Mod b) {
	assert(b.num != 0);
	return Mod(a) * inv(b);
}
Mod operator/=(Mod &a, const Mod b) {
	assert(b.num != 0);
	return a = a * inv(b);
}

#define MAX_MOD_N 1024000

Mod fact[MAX_MOD_N], factinv[MAX_MOD_N];
void init() {
	fact[0] = Mod(1); factinv[0] = 1;
	for (int i = 0; i < MAX_MOD_N - 1; ++i) {
		fact[i + 1] = fact[i] * Mod(i + 1);
		factinv[i + 1] = factinv[i] / Mod(i + 1);
	}
}
Mod comb(const int a, const int b) {
	return fact[a] * factinv[b] * factinv[a - b];
}
Mod dp[201][202][202];
int main() {
	memset(dp, 0, sizeof(dp));
	int N; cin >> N;
	vector<int>vs(N);
	for (int i = 0; i < N; ++i) {
		char c; cin >> c;
		if (c == '-') {
			vs[i] = 0;
		}
		else if (c == 'U') {
			vs[i] = -1;
		}
		else {
			vs[i] = 1;
		}
	}
	dp[0][0][0] = 1;
	for (int i = 0; i < N; ++i) {
		for (int downing = 0; downing < 200; ++downing) {
			for (int upping = 0; upping < 200; ++upping) {
				if (vs[i] == 0) {
					dp[i + 1][downing][upping] += dp[i][downing][upping];
				}
				else if (vs[i] == 1) {
					//??????
					if (downing >= 1) {
						dp[i + 1][downing - 1][upping - 1] += dp[i][downing][upping] * downing*downing;
					}
					//??????
					dp[i + 1][downing][upping] += dp[i][downing][upping] * downing;
					
				}
				else {
					//??????
					dp[i + 1][downing + 1][upping+1] += dp[i][downing][upping];

					//??????
					if (upping >= 1) {
						dp[i + 1][downing][upping] += dp[i][downing][upping]*downing;
					}
				}
			}
		}
	}
	cout << dp[N][0][0] << endl;
	
	return 0;
}

Measured memory_bytes: 43140