#!/usr/bin/env python3
import sys
def ask(y):
    print('?', y)
    sys.stdout.flush()
    return int(input())
def ans(y):
    print('!', y)
    sys.exit()

m = 100
p = ask(m)
if p == 1:
    l = m
    r = 10**9 # (l, r]
elif p == -1:
    l = 10-1
    r = m-1
else:
    ans(m)
for i in range(1,100):
    m = (l+r+1) // 2
    p = ask(m-i)
    if p == 1:
        l = m
    elif p == -1:
        r = m
    else:
        ans(m)