import sys


sys.setrecursionlimit(10**8)


def debug(*args):
    print(*args, file=sys.stderr)


ok = 0
ng = 10**9 + 1

for _ in range(30):
    mid = (ok + ng) // 2
    print(mid, flush=True)
    r = int(input())
    if r == 0:
        ng = mid
    else:
        exit()