def ask(x):
    print(f'? {x}')
    resp = int(input())
    return resp


lo = 10
hi = 10 ** 9
cnt = 0
while lo <= hi:
    m = (lo + hi) // 2
    resp = ask(m)
    match resp:
        case -1:
            hi = m - 1
        case 0:
            print(f'! {m+cnt}')
            break
        case 1:
            lo = m + 1

    cnt += 1