N,M = map(int, input().split())
S = input().strip()
A = []
C = []
W = []
for i in range(2*(N+M)):
    if S[i]=="A":
        A.append(i)
    elif S[i]=="C":
        C.append(i)
    else:
        W.append(i)
flag = True
for i in range(M):
    if A[i]>C[i]:
        flag = False
        break
if not flag:
    print("No")
else:
    A = A[M:]
    for i in range(N):
        if A[i]<W[i]:
            flag = False
            break
    if flag:
        print("Yes")
    else:
        print("No")