import sys

def ST(): return pin().rstrip()
def IN(): return int(pin())
def IM(): return map(int, pin().split())
def IL(): return list(map(int, pin().split()))
def SR(n:int): return [pin().rstrip() for _ in range(n)]
def IMatrix(n:int): return [IL() for _ in range(n)]

##-----------------
import random
import math
import bisect
import itertools
from collections import defaultdict, deque
#from sortedcontainers import SortedList
##-----------------

r = 10**9+1
l = 0
for i in range(30):
	c = (r+l)//2
	print(c, flush=True)
	try:
		R = int(input())
	except Exception:
		exit()
	if R:
		l = c
	else:
		r = c+1
print(l)