n,m = map(int,input().split())
wa = []; ac = []; i = j = 0
for v in input():
    if v=="W": wa.append(v)
    elif v=="C": ac.append(v)
    elif i<m: ac.append(v); i += 1
    else: wa.append(v); i += 1
for v in wa:
    if v=="W": j += 1
    else: j -= 1
    if j<0: exit(print("No"))
for v in ac:
    if v=="A": j += 1
    else: j -= 1
    if j<0: exit(print("No"))
print("Yes")