// yukicoder: No.253 ロウソクの長さ
// 2019.5.10 bal4u

#include <stdio.h>

int x = 1000000000;
int answer(int y) {
	int r;
	if (x < y) r = -1;
	else if (x > y) r = 1;
	else if (y == x) r = 0;
	x--;
	return r;
}

int ask(int y) {
	int a;
#if 0
	a = answer(y);
#else
	printf("?%d\n", y), fflush(stdout);
	scanf("%d", &a);
#endif
	return a;
}

int main()
{
	int a, k, l, r, m, ans;

	m = 100;
	a = ask(m), k = 1;
	if (a == 0) ans = m;
	else {
		k = 1;
		if (a > 0) l = m, r = 1000000001;
		else l = 9, r = m-1;
		while (l < r) {
	        m = (l + r) >> 1;
			a = ask(m);
			if (a == 0) { l = m; break; }
			k++;
		    if (a > 0) l = m, r--;
			else l--, r = m-1;
		}
		ans = l + k;
    }
	printf("!%d\n", ans), fflush(stdout);
	return 0;
}