N, M = map(int, input().split())
S = input()
A = C = W = B = 0
for i in range((N + M) * 2):
	if S[i] < "C": A += 1
	elif S[i] > "C":
		B += M + W < A
		W += 1
	else:
		C += 1
		B += A < C
print("No"if B else"Yes")