# coding:UTF-8 import sys MOD = 10 ** 9 + 7 INF = float('inf') # 二分探索 imin = 0 imax = 10 ** 9 + 1 print("? {}".format(99)) check = int(input()) if check == 0: print("! {}".format(99)) elif check == -1: time = 1 while True: print("? {}".format(0)) check = int(input()) if check == 0: break time += 1 print("! {}".format(time)) elif check == 1: time = 0 while True: imid = imin + (imax - imin) // 2 print("? {}".format(imid - time)) check = int(input()) # 2分探索する。 if check == 0: res = imid break elif check == 1: imin = imid else: imax = imid time += 1 print("! {}".format(res))