fn query (x: u64) -> bool {
	println!("? {}", x);
	let mut s = String::new();
	std::io::stdin().read_line(&mut s).ok();
	s.trim() == "out"
}

fn main() {
	let mut safe = 0;
	let mut out = 1000;
	while out - safe > 1 {
		let m = (safe + out) / 2;
		if query(m) && query(m + 1) { out = m; }
		else { safe = m; }
	}
	let ans = if !query(safe + 1) { safe + 1}
	else { safe };
	println!("! {}", ans);
}