import sys
input=lambda: sys.stdin.readline().rstrip()
print("?",100,flush=True)
ans=int(input())
if ans==0:
  print("!",100,flush=True)
elif ans==-1:
  l,r=10,100
  ct=1
  while r-l>1:
    mid=(l+r)//2
    print("?",max(0,mid-ct),flush=True)
    ct+=1
    ans=int(input())
    if ans==0:
      print("!",mid,flush=True)
      break

    elif ans==1:
      l=mid
    else:
      r=mid
  else:
    print("?",max(0,r-ct),flush=True)
    ct+=1
    ans=int(input())
    if ans==0:
      print("!",r,flush=True)
    else:
      print("!",l,flush=True)
else:
  l,r=100,10**9
  ct=1
  while r-l>1:
    mid=(l+r)//2
    print("?",max(0,mid-ct),flush=True)
    ct+=1
    ans=int(input())
    if ans==0:
      print("!",mid,flush=True)
      break

    elif ans==1:
      l=mid
    else:
      r=mid
  else:
    print("?",max(0,r-ct),flush=True)
    ct+=1
    ans=int(input())
    if ans==0:
      print("!",r,flush=True)
    else:
      print("!",l,flush=True)