import sys

max_num = 1000000000
ck_num = max_num // 2
span = max_num // 2

while True:
    print("?",ck_num)
    ans = int(input())
    span = span // 2
    if ans == 1:
        ck_num += span
    else:
        ck_num -= span
    if span == 1:
        break

ck_num -= 3
for i in range(10):
    print("?", ck_num)
    ans = int(input())
    if ans == 1:
        ck_num += 1
    else:
        print("!", ck_num - 1)
        sys.exit()