x = int(input())

def popcount(x):
    res = 0
    while x > 0:
        if x % 2 == 1:
            res += 1
        x //= 2
    return res

for i in range(70):
    if i == 0: continue
    if popcount(i ^ x) == i and (i ^ x) <= 2 * (10 ** 18):
        print(i ^ x)
        exit(0)

print(-1)