import sys

# sys.setrecursionlimit(200005)
# sys.set_int_max_str_digits(200005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()

dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
# inf = -1-(-1 << 31)
inf = -1-(-1 << 62)

# md = 10**9+7
md = 998244353

from itertools import product

def naive(n,m):
    ans=0
    arr=[]
    for p in product(range(m+1),repeat=n-1):
        x=0
        for a in p:x^=a
        if x>m:continue
        s=sum(p)+x
        if s>ans:
            ans=s
            arr=list(p)+[x]
    return ans,arr

# n=5
# m=(1<<n)-2
n,m=LI()
if n==1:
    ans=0
elif (m+2).bit_count()==1 and m.bit_length()==n:
    ans=(m+1)*(n-1)
elif n&1 and m.bit_count()>1:
    i=32
    cnt=0
    while cnt<2:
        i-=1
        cnt+=m>>i&1
    a=(1<<i+1)-1
    b=m^a
    ans=max(a+b+m*(n-2),m*(n-1))
else:
    ans=(n-(n&1))*m
# x,y=naive(n,m)
# if ans!=x:
#     print(n,m,ans,x,y)
print(ans)

# 5 30 122 124 [15, 23, 27, 29, 30]