import sys
mid = 1
left=0
right=1000000000
res = 1
while left<right:
    mid=(right+left)/2
    print ("? %d" % mid)
    sys.stdout.flush()
    res = int(input())
    if res==1:
        mid=left+1
    else:
        mid=right+1
printf("! %d" % mid)
sys.stdout.flush()