N,K = map(int, input().split())

if K <= N//2:
    ans = (K+2)//2*2
    if K%2 == 0 or (N%2 == 0 and N//2 == K):
        ans -= 1
else:
    if N%2 == 0:
        ans = N//2
    elif K%2 == 0:
        ans = min(N, K+1)
    else:
        ans = min(N-1, (K+1)//2*2)

print(ans)