l = 1
r = 10**6+1
N = 10**9

def main1(l, r, x0):
    if l+1 == r:
        print("!", l)
        return
    m = (l + r) >> 1
    if m <= x0:
        x1 = m - 1 - (x0 - m)
        if abs(x1) > N:
            main0(l, r)
            return
        print("?", x1)
        t = int(input())
        if t:
            main1(l, m, x1)
        else:
            main1(m, r, x1)
    else:
        x1 = m + m - 1 - x0
        if abs(x1) > N:
            main0(l, r)
        print("?", x1)
        t = int(input())
        if t:
            main1(m, r, x1)
        else:
            main1(l, m, x1)
    
def main0(l, r, f = 1):
    if l+1 == r:
        print("!", l)
        return
    m = (l + r) >> 1
    print("?", m)
    if f:
        input()
    main1(l, r, m)

main0(l, r, 0)