n, m = map(int, input().split())
if n == 1:
    print(0)
    exit()
if n % 2 == 0:
    print(m * n)
    exit()
草 = [0] * (35)
s = bin(m)[2:].zfill(35)
f = -1
for i in range(0, 35):
    if s[i] == "1" and f == -1:
        f = i
    草[i] = (n-2 if s[i] == "1" else 0)
for i in range(f+1, 35):
    草[i] += 1
ans = 0
for i in range(35):
    ans += 草[i] * (2**(34-i))
    if 草[i] % 2 == 1:
        ans += (2**(34-i))
print(ans)