import sys
from sys import stdin
ok = 0
ng = 2*10**9
while ng - ok > 1:
    mid = (ok + ng) // 2
    print(mid,end="\n",flush=True)
    r = sys.stdin.readline().rstrip()
    r = int(r)
    if r == 1:
        ok = mid
        exit()
    elif r == 0:
        ng = mid
    else:
        exit()