import sys

mem = []
print("? 100")
sys.stdout.flush()
res = int(input())
mem.append((100, res))

if res == -1:
  while res != 0:
    print("? 1")
    sys.stdout.flush()
    res = int(input())
    mem.append((1, res))
elif res == 1:
  ng = 0
  ok = 10 ** 9
  while res != 0:
    mid = (ok + ng) // 2
    print(f"? {mid - len(mem)}")
    sys.stdout.flush()
    res = int(input())
    mem.append((mid - len(mem), res))

    if res < 0:
      ok = mid
    else:
      ng = mid

print(f"! {mem[-1][0] + len(mem) - 1}")
sys.stdout.flush()