#include <iostream>
using namespace std;

char ask(int Y){
	cout << "? " << Y << endl;
	char res;
	cin >> res;
	return res;
}

int solve(){
	int askCount = 0;
	for(int i=2;i<=50;i++,askCount++){
		char res = ask(i);
		if(res == '<'){
			return i - 1 + askCount;
		}
		if(res == '='){
			return i + askCount;
		}
	}
	// [lo, hi)
	int lo = 50, hi = 1e9 - askCount + 1;
	for(;;++askCount){
		int mid = (lo + hi) / 2;
		char res = ask(mid);
		if(res == '='){
			return mid + askCount;
		}
		if(res == '<'){
			hi = mid;
		} else {
			lo = mid + 1;
		}
		if(hi - lo == 1){
			return lo + askCount;
		}
		--lo;
		--hi;
	}
	return -1;
}

int main(){
	int Y = solve();
	cout << "! " << Y << endl;
	return 0;
}