N = int(input())
for i in range(N//2):
  a,b = 2*i, 2*i+1
  print('?',a,b)
  c = int(input())
  if a == c:
    print('!',b)
    exit()
  if b == c:
    print('!',a)
    exit()
print('!',N-1)
exit()