def query(x):
    print('?',x,  flush = True)
    ret = int(input())
    return ret


n = int(input())
left = 1
right = n

while abs(right - left) > 1:
    now = (left + right) // 2
    ret = query(now)
    if 2 * ret - now > 0:
        left = now
    elif 2 * ret - now < 0:
        right = now
    else:
        print('!', 1,  now, flush = True)
        break