import sys
input = sys.stdin.readline

MIN=1
MAX=10**6
mae=MIN
count=0
print("?",MIN,flush=True)


while MIN!=MAX:
    half=(MIN+MAX)//2

    tugi=mae+(half-mae)*2

    print("?",tugi,flush=True)   

    ANS=int(input())

    if ANS==1:
        MIN=half
    else:
        MAX=half

    mae=tugi

print("!",MIN,flush=True)