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

#ifdef _RUTHEN
#include <debug.hpp>
#else
#define show(...) true
#endif

using ll = long long;
#define rep(i, n) for (int i = 0; i < (n); i++)
template <class T> using V = vector<T>;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int N, M;
    cin >> N >> M;
    string S;
    cin >> S;
    int K = 2 * (N + M);
    deque<int> quew, quea;
    bool ok = true;
    for (int i = 0; i < K; i++) {
        if (S[i] == 'C') {
            if (quea.size() == 0) {
                ok = false;
                break;
            }
            quea.pop_front();
        } else if (S[i] == 'W') {
            quew.push_back(i);
        } else {
            quea.push_back(i);
        }
    }
    if (ok) {
        for (int i = 0; i < quea.size(); i++) {
            if (quew[i] > quea[i]) {
                ok = false;
                break;
            }
        }
    }
    cout << (ok ? "Yes" : "No") << '\n';
    return 0;
}