import sys
#sys.setrecursionlimit(500000)
def I(): return int(sys.stdin.readline().rstrip())
def MI(): return map(int,sys.stdin.readline().rstrip().split())
def TI(): return tuple(map(int,sys.stdin.readline().rstrip().split()))
def LI(): return list(map(int,sys.stdin.readline().rstrip().split()))
def SI(): return sys.stdin.readline().rstrip()
def LS(): return list(sys.stdin.readline().rstrip())
#for i, pi in enumerate(p):
from collections import defaultdict,deque
import bisect
import itertools

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