from collections import defaultdict, Counter, deque
from itertools import groupby, accumulate, combinations, permutations, product, combinations_with_replacement
from bisect import bisect_left, bisect_right
from operator import itemgetter
import math
from heapq import heapify, heappush, heappop

LMI=lambda:list(map(int, input().split()))
LMS=lambda:list(map(str, input().split()))
MI=lambda:map(int, input().split())
MS=lambda:map(str, input().split())
II=lambda:int(input())
IS=lambda:input().split()
LI=lambda:list(input())

ok, ng = 10**9, 0

while True:
		#真ん中の値を計算
    mi = (ok + ng) // 2
    print(mi)
    r=II()

    if r==1 or r==-1:
        exit()
    elif r==0:
        ok = mi