#include <bits/stdc++.h>

using namespace std;

inline int toInt(string s) {int v; istringstream sin(s);sin>>v;return v;}
template<class T> inline string toString(T x) {ostringstream sout;sout<<x;return sout.str();}
template<class T> inline T sqr(T x) {return x*x;}

typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<string> vs;
typedef pair<int, int> pii;
typedef long long ll;

#define all(a)  (a).begin(),(a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define pb push_back
#define mp make_pair
#define each(i,c) for(typeof((c).begin()) i=(c).begin(); i!=(c).end(); ++i)
#define exist(s,e) ((s).find(e)!=(s).end())
#define range(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,n)  range(i,0,n)
#define clr(a,b) memset((a), (b) ,sizeof(a))
#define dump(x)  cerr << #x << " = " << (x) << endl;
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;

const double eps = 1e-10;
const double pi  = acos(-1.0);
const ll INF =1LL << 62;
const int inf =1 << 29;

const ll mod=1000000007;
ll dp[210][210][210];
char c[210];

int main(void){
	int n;
	cin >> n;
	rep(i,n) cin >> c[i];
	dp[0][0][0]=1LL;
	rep(i,n)rep(x,n+1)rep(y,n+1){
		if(dp[i][x][y]==0) continue;
		switch(c[i]){
			case 'U':
				dp[i+1][x][y]+=dp[i][x][y]*x;
				dp[i+1][x][y]%=mod;
				dp[i+1][x+1][y+1]+=dp[i][x][y];
				dp[i+1][x+1][y+1]%=mod;
				break;
			case '-':
				dp[i+1][x][y]+=dp[i][x][y];
				dp[i+1][x][y]%=mod;
				break;
			case 'D':
				dp[i+1][x][y]+=dp[i][x][y]*y;
				dp[i+1][x][y]%=mod;
				if(x-1>=0&&y-1>=0){
					dp[i+1][x-1][y-1]+=dp[i][x][y]*x*y;
					dp[i+1][x-1][y-1]%=mod;
				}
				break;
		}
	}
	cout << dp[n][0][0] << endl;
	return 0;
}