#include <bits/stdc++.h>
using namespace std;
//using namespace atcoder;
//using mint = modint1000000007;
//const int mod = 1000000007;
//using mint = modint998244353;
//const int mod = 998244353;
//const int INF = 1e9;
//const long long LINF = 1e18;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i,l,r)for(int i=(l);i<(r);++i)
#define rrep(i, n) for (int i = (n-1); i >= 0; --i)
#define rrep2(i,l,r)for(int i=(r-1);i>=(l);--i)
#define all(x) (x).begin(),(x).end()
#define allR(x) (x).rbegin(),(x).rend()
#define endl "\n"
#define P pair<int,int>
template<typename A, typename B> inline bool chmax(A& a, const B& b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A& a, const B& b) { if (a > b) { a = b; return true; } return false; }
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int n, m; cin >> n >> m;
	string s; cin >> s;
	stack<int>stw, sta;
	bool chk = true;
	rep(i, s.size()) {
		if ('W' == s[i]) {
			stw.push(i);
		}
		else if ('A' == s[i]) {
			sta.push(i);
		}
		else {
			if (sta.empty()) {
				chk = false;
				break;
			}
			sta.pop();
		}
	}
	if (chk) {
		while (!sta.empty()) {
			if (stw.top() > sta.top()) {
				chk = false;
				break;
			}
			stw.pop();
			sta.pop();
		}
	}
	if (chk)cout << "Yes" << endl;
	else cout << "No" << endl;
	return 0;
}