N = int(input())
cand = list(range(1, N + 1))

while len(cand) > 2:
    nxt = []
    while len(cand) >= 2:
        a = cand.pop()
        b = cand.pop()
        print("? {} {}".format(a, b))
        ans = int(input())
        nxt.append(ans)
    if cand:
        nxt.append(cand)
    cand = nxt

a, b = cand
print("? {} {}".format(a, b))
ans = int(input())
print("! {}".format(a ^ b ^ ans))