mod = 1000000007
eps = 10**-9


def main():
    import sys
    input = sys.stdin.readline

    def ask(k):
        print("?", k)
        sys.stdout.flush()
        return int(input())

    N = int(input())

    s0 = ask(N // 2)
    if s0 * 2 == N or s0 == 0:
        print("!", 2, N - 1)
        sys.stdout.flush()
        exit()
    s0 = s0 - (N // 2 - s0)
    if s0 == 0:
        print("!", 1, N // 2)
        sys.stdout.flush()
        exit()

    l = N // 2
    r = N + 1
    for _ in range(19):
        mid = (l + r) // 2
        s = ask(mid)
        s = s - (mid - s)
        if s == 0:
            print("!", 1, mid)
            sys.stdout.flush()
            exit()
        if s * s0 > 0:
            l = mid
        else:
            r = mid


if __name__ == '__main__':
    main()