end = 10 ** 3 start = 0 while end - start > 1: mid = (start + end) // 2 print('?',mid) ans = input() if ans == 'safe': start = mid else: print('?',mid-1) ans = input() if ans == 'safe': start = mid-1 if end - start == 2: end -= 1 elif end - start == 3: print('?',mid + 1) ans = input() if ans == 'safe': start = ans else: end = mid - 1 else: end = mid-1 print('!',start)