import sys
input = sys.stdin.readline

MIN=1
MAX=1000000
mae=MIN
count=0
print("?",MIN,flush=True)


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

    tugi=round(mae+(half-mae)*2)

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

    ANS=int(input())

    if ANS==1:
        if mae <tugi:
            MIN=half
        else:
            MAX=half
    else:
        if mae <tugi:
            MAX=half-1
        else:
            MIN=half+1

    mae=tugi

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