N,M=map(int,input().split())
if N%2==0:
    print(N*M)
else:
    A1=0
    A2=0
    for i in range(len(bin(M)[2:])):
        if (M>>i)&1==0:
            A1+=1<<i
            A2+=1<<i
        else:
            if A1+1<<i<=M:
                A1+=1<<i
            else:
                A2+=1<<i
    print((N-2)*M+A1+A2)