N,M=map(int,input().split())
if N%2 == 0:
    print(N*M)
    exit()
ans=0
free = 0
for i in range(M.bit_length()-1,-1,-1):
    d = 2**i
    if d&M:
        ans+=(N//2)*2*d
        free+=1
    else:
        ans+=(free//2)*2*d
print(ans)