import sys
x = int(input())
for i in range(x - 100, x + 100):
  if i <= 0:
    continue
  cnt = 0
  a = i
  for j in range(61, -1, -1):
    if a >= (2 ** j):
      a -= (2 ** j)
      cnt += 1
  if (i ^ cnt) == x:
    print(i)
    sys.exit()
print(-1)