#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <locale>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <typeinfo>
#include <utility>
#include <valarray>
#include <vector>
#include <climits>
#include <cstring>
#include <cassert>


using namespace std;
#define SZ(x) (int)(x.size())
#define REP(i, n) for(int i=0;i<n;++i)
#define FOR(i, a, b) for(int i=a;i<b;++i)
#define RREP(i, n) for(int i=n-1;i>=0;--i)
#define RFOR(i, a, b) for(int i=b-1;i>=a;--i)

#define all(x) begin(x),end(x)
#define dump(x) cerr<<#x<<" = "<<(x)<<endl
#define debug(x) cerr<<#x<<" = "<<(x)<<" (L"<<__LINE__<<")"<< endl;

using ll = long long;
using vi = vector<int>;
using vvi = vector<vi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using P = pair<int, int>;
const double eps = 1e-8;
const ll MOD = 1000000007;
const int INF = INT_MAX / 2;
const ll LINF = LLONG_MAX / 2;

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 (b < a) {
        a = b;
        return true;
    }
    return false;
}


template<typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> p) {
    os << p.first << ":" << p.second;
    return os;
}

template<class T>
ostream &operator<<(ostream &os, const vector<T> &v) {
    os << "[";
    REP(i, SZ(v)) {
        if (i) os << ", ";
        os << v[i];
    }
    return os << "]";
}

template<class T1, class T2>
ostream &operator<<(ostream &os, const map<T1, T2> &mp) {
    os << "[";
    for (auto it = mp.begin(); it != mp.end(); ++it) {
        if (it != mp.begin()) {
            os << ", ";
        }
        os << *it;
    }
    return os << "]";
}

// edit

int add(ll x, ll y) {
    return (x + y) % MOD;
}

int mul(ll x, ll y) {
    return (x * y) % MOD;
}

void print_dp(vector<vector<ll>> dp) {
    int n = dp.size();
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < n; ++j) {
            cout << dp[i][j] << " ";
        }
        cout << endl;
    }
    cout << "---------------------------" << endl;
}

int calc(vector<char> c) {
    int n = c.size();

    vector<vector<ll>> dp(n + 1, vector<ll>(n + 1)), dp_new(n + 1, vector<ll>(n + 1));
    dp[0][0] = 1;
//    print_dp(dp);

    for (int i = 0; i < n; ++i) {
        for (int p = 0; p < n; ++p) {
            for (int q = 0; q < n; ++q) {
                if (c[i] == 'U') {
                    {
                        dp_new[p][q] += p * dp[p][q] % MOD;
                        dp_new[p][q] %= MOD;
                    }
                    {
                        dp_new[p + 1][q + 1] += dp[p][q];
                        dp_new[p + 1][q + 1] %= MOD;
                    }
                }

                if (c[i] == 'D') {
                    if (p > 0 && q > 0) {
                        dp_new[p - 1][q - 1] += p * q * dp[p][q] % MOD;
                        dp_new[p - 1][q - 1] %= MOD;
                    }
                    {
                        dp_new[p][q] += q * dp[p][q] % MOD;
                        dp_new[p][q] %= MOD;
                    }
                }
            }
        }

        swap(dp, dp_new);

        for (int j = 0; j < dp_new.size(); ++j) {
            fill(all(dp_new[j]), 0);
        }
//        print_dp(dp);
    }

    return (int) (dp[0][0] % MOD);

}

void solve() {
    int n;
    cin >> n;
    vector<char> c;
    REP(i, n) {
        char tmp;
        cin >> tmp;
        if (tmp != '-') {
            c.push_back(tmp);
        }
    }

    int ans = calc(c);
    cout << ans << endl;

}


int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
//    std::ifstream in("input.txt");
//    std::cin.rdbuf(in.rdbuf());

    solve();


    return 0;
}



Measured memory_bytes: 3436