#include <bits/stdc++.h>
using namespace std;

bool is_kakko(string &s)
{
	int n = (int)s.size();
	int cnt = 0;
	for(int i = 0; i < n; i++)
	{
		if(s[i] == '(') cnt++;
		else
		{
			cnt--;
			if(cnt < 0) return false;
		}
	}
	if(cnt != 0) return false;
	return true;
}

int main()
{
	int n, m; string s;
	cin >> n >> m >> s;
	string c1, c2;
	int cnt = 0;
	for(int i = 0; i < 2 * (n + m); i++)
	{
		if(s[i] == 'C') c2 += ')';
		else if(s[i] == 'W') c1 += '(';
		else
		{
			if(cnt < m) c2 += '(';
			else c1 += ')';
			cnt++;
		}
	}
	if(is_kakko(c1) && is_kakko(c2)) cout << "Yes" << endl;
	else cout << "No" << endl;
	return 0;
}