import sys
l, r = 1, 10**9

while l < r-1:
    ask = (l+r)/2
    print '?', ask#, 'l=', l, 'r=', r
    sys.stdout.flush()
    rep = raw_input()
    if rep == '1':
        l = ask
    else:
        r = ask
else:
    print '?', r
    sys.stdout.flush()
    rep = raw_input()
    if rep == '1':
        ans = r
    else:
        ans = l

print '!', ans
exit()