fn main() {
    let mut l = 0u64;
    let mut r = 10u64.pow(10);
    while r - l > 1 {
        let mid = (l + r) >> 1;
        println!("? {}", mid);
        let mut s = String::new();
        std::io::stdin().read_line(&mut s).ok();
        let s = s.trim();
        if s == "1" {
            l = mid;
        } else {
            r = mid;
        }
    }
    println!("! {}", l);
}