#define _USE_MATH_DEFINES
#include <algorithm>
#include <cstdio>
#include <functional>
#include <iostream>
#include <cfloat>
#include <climits>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <time.h>
#include <vector>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> i_i;
typedef pair<ll, int> ll_i;
typedef pair<double, int> d_i;
typedef pair<ll, ll> ll_ll;
typedef pair<double, double> d_d;
struct edge { int u, v; ll w; };

ll MOD = 1000000007;
ll _MOD = 1000000009;
double EPS = 1e-10;

int main() {
	string s;
	int n; cin >> n;
	while (n--) {
		char c; cin >> c;
		if (c != '-') s.push_back(c);
	}
	n = s.length();
	int u = 0;
	vector<int> dp(n + 1);
	dp[0] = 1;
	for (int i = 0; i < n; i++) {
		if (s[i] == 'D')
			for (int j = 0; j <= n; j++)
				dp[j] = (ll)dp[j] * (u - j) % MOD;
		for (int j = n - 1; j >= 0; j--)
			dp[j + 1] = (dp[j + 1] + (ll)dp[j] * (u - j)) % MOD;
		if (s[i] == 'U') u++;
	}
	cout << dp[u] << endl;
}