import sys low = 0 high = int(1e9 + 1) mid = 1000 count = 0 print("?", mid) sys.stdout.flush() res = int(input()) if res == 0 : print("! 1000") sys.stdout.flush() elif res == -1 : high = mid mid = (low + high) // 2 - 1 while True : print("?", mid) sys.stdout.flush() res = int(input()) count += 1 if res == 0 : print("!", mid + count) sys.stdout.flush() sys.exit() elif res == -1 : high = mid else : low = mid mid = (low + high) // 2 - 1 elif res == 1 : low = 900 mid = (low + high) // 2 - 1 while True : print("?", mid) sys.stdout.flush() res = int(input()) count += 1 if res == 0 : print("!", mid + count) sys.stdout.flush() sys.exit() elif res == -1 : high = mid else : low = mid mid = (low + high) // 2 - 1