N,M=map(int,input().split())
if N==1 : exit(print(0))
if N%2==0 : exit(print(N*M))
A=[]
for i in range(60):
    if M>>i&1 : A.append(i)
ans=M*(N-1)
A.reverse()
if 2<=len(A):
    for i in range(A[1],-1,-1):
        if i not in A : ans+=1<<i+1
print(ans)