DEBUG = 0
ans = 10

def query(x):
    print(f"? {x}")
    sys.stdout.flush()
    if DEBUG:
        return x <= ans
    else:
        return int(input())

import sys
ok = 0
ng = 10**9+1
while ng-ok > 1:
    mid = (ng+ok)//2
    if query(mid):
        ok = mid
    else:
        ng = mid
print(f"! {ok}")
sys.stdout.flush()