import sys
readline = sys.stdin.readline

# DEBUG = True
DEBUG = False

class Interactive:
    def __init__(self):
        self.ques_cnt = 0
        self.create_data()
        
    def create_data(self):
        import random
        x = random.randint(1, 10**9)
        self.x = x
        print('created:', x)
        
    def resp_ques(self, *args):
        self.ques_cnt += 1
        if len(args) != 1:
            raise ValueError
        y = args[0]
        if self.x >= y:
            return '1\n'
        else:
            return '0\n'
            
    def resp_ans(self, *args):
        if len(args) != 1:
            raise ValueError
        y = args[0]
        if self.x == y:
            print('AC!')
            print('ques_cnt:', self.ques_cnt)
        else:
            print('WA')
            
if DEBUG:
    interactive = Interactive()
    
def question(*args, offset=None):
    if offset is None:
        print(*args, flush=True)
    else:
        print(offset, *args, flush=True)
    if DEBUG:
        resp = interactive.resp_ques(*args)
        print(resp)
        return resp
    else:
        return readline()
    
def answer(*args, offset=None):
    if offset is None:
        print(*args, flush=True)
    else:
        print(offset, *args, flush=True)
    if DEBUG:
        interactive.resp_ans(*args)
    else:
        exit()

left = 0
right = 10**9 + 10 # xより大きい
while left + 1 < right:
    x = (left+right) // 2
    resp = int(question(x))
    if resp:
        left = x
    else:
        right = x

answer(left)