#yuki_246
import sys

l=1
r=10**9+1
cnt=0
while l<r and cnt<100:
 cnt+=1
 mid=(l+r)/2
 print "? %d" % mid
 sys.stdout.flush()
 res=int(raw_input())
 if res==1:
  l=mid
 else:
  r=mid
print "! %d" % l
sys.stdout.flush()