n, m = map(int, input().split())
if n % 2 == 0:
    print(n * m)
    exit()
ans = 0
frees = 0
for k in range(m.bit_length())[::-1]:
    if m >> k & 1 == 0:
        ans += frees // 2 * 2 << k
    else:
        ans += (n - 1) << k
        frees = min(frees + 1, n)
print(ans)