n = int(input())
m = n//2
a=0
b=1
print('?',a,b)
for i in range(0,m):
    z = int(input())
    if a == z:
        print('!',b)
        break
    elif b == z:
        print('!',a)
        break
    else:
        a += 2
        b += 2
        if a == n or b == n:
            print('!',n-1)
        else:
            print('?',a,b)