#!/usr/bin/env python3
from collections import deque


dpos4 = ((1, 0), (0, 1), (-1, 0), (0, -1))
dpos8 = ((0, -1), (1, -1), (1, 0), (1, 1), (0, 1), (-1, 1), (-1, 0), (-1, -1))
mod1 = 10**9 + 7
mod2 = 998244353
inf = 1 << 60


def main():
    N, M = map(int, input().split())

    W = []
    C = []
    A = deque()
    S = input()
    for i in range(len(S)):
        if S[i] == "W":
            W.append(i)
        elif S[i] == "C":
            C.append(i)
        else:
            A.append(i)

    def solve():
        for c in C:
            if not A or A[0] >= c:
                return False
            A.popleft()
        for w in W:
            if not A or A[0] <= w:
                return False
            A.popleft()
        return True

    if solve():
        print("Yes")
    else:
        print("No")


if __name__ == "__main__":
    main()