R,B=map(int,input().split())
S=input()
queue=[""]
for s in S:
    if s=="W":
        queue=[ss+s for ss in queue]
    else:
        queue=[ss+s for ss in queue]+[ss for ss in queue]
ans=0
for S in queue:
    N=len(S)
    ok=True
    for i in range(N-R):
        if S[i]=="R" and S[i+R]=="R":
            ok=False
    for i in range(N-B):
        if S[i]=="B" and S[i+B]=="B":
            ok=False
    if ok:
        ans=max(ans,N)
print(ans)