def simulate(w)
    return  (202>=w) ? 1 : 0
end

l=1;h=10**9
while h-l>0
    m=(h+l)/2;
    puts "? "+m.to_s;STDOUT.flush
    if 0==gets.to_i #simulate(m)
        h=m-1
    else
        break if h-l<=1
        l=m
    end
end
puts "! "+l.to_s