from collections import defaultdict, deque, Counter
# from functools import cache
# import copy
from itertools import combinations, permutations, product, accumulate, groupby, chain
# from more_itertools import distinct_permutations
from heapq import heapify, heappop, heappush, heappushpop
import math
import bisect
# from pprint import pprint
from random import randint, shuffle, randrange
# from sortedcontainers import SortedSet, SortedList, SortedDict
import sys
# sys.setrecursionlimit(2000000)
input = lambda: sys.stdin.readline().rstrip('\n')
inf = float('inf')
mod1 = 10**9+7
mod2 = 998244353
def ceil_div(x, y): return -(-x//y)

#################################################   

def judge(x):
    print(x, flush=True)
    r = int(input())
    if r == 1:
        exit()
    return False

ok, ng = 1, 10**9
while(abs(ok-ng)>1):
    mid = (ok+ng)//2
    if judge(mid):
        ok = mid
    else:
        ng = mid