n,m=map(int,input().split())
s=input()
A=[]
C=[]
W=[]
for i in range(2*(n+m)):
  if s[i]=='W':
    W.append(i)
  elif s[i]=='A':
    A.append(i)
  else:
    C.append(i)

ans='Yes'
A1=A[:m]
A2=A[m:]
for i in range(m):
  if A1[i]>C[i]:
    ans='No'
for i in range(n):
  if A2[i]<W[i]:
    ans='No'
print(ans)