def main():
   
   top = 10 ** 9
   under = 1
   
   while top - under > 1:
   	  mid = (top + under) // 2
   	  print('?', mid)
   	  N = int(input())
   	  if N == 1:
   	  	  under = mid
   	  else:
   	  	  top = mid
   
   print('!', under)
   
if __name__ == '__main__':
    main()