C = ["x"] + list(input()) + list(input()) + ["x"]
ans = 0
cnt = 0
for i in range(1,len(C)):
    if C[i] == C[i-1] == "o":
        cnt += 1
    else:
        ans = max(ans,cnt+1) if cnt > 0 else ans
        cnt = 0
print(ans)