#!/usr/bin/python
import sys

lo, hi = 1, int(1e9)

for _ in xrange(50):
    y = (lo + hi) / 2
    print '? {}'.format(y)
    sys.stdout.flush()
    res = int(raw_input())
    if res == 1:
        lo = y
    else:
        hi = y

x = y - 5
for _ in xrange(10):
    print '? {}'.format(x)
    sys.stdout.flush()
    res1 = int(raw_input())
    print '? {}'.format(x+1)
    sys.stdout.flush()
    res2 = int(raw_input())
    if res1 == 1 and res2 == 0:
        print '! {}'.format(x)
        sys.stdout.flush()
        exit(0)
    x += 1
print 'nya'