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

#include <stdio.h>
#include <stdlib.h>

#define gc() getchar()
#define pc(c) putchar(c)

int in()
{
	int n = 0, c = gc();
	if (c == '-') {	c = gc();
		do n = 10*n + (c & 0xf), c = gc(); while (c >= '0');
		return -n;
	}
	do n = 10*n + (c & 0xf), c = gc(); while (c >= '0');
	return n;
}

void out(int n)
{
	int i;
	char ob[20];

	if (!n) pc('0');
	else {
		i = 0; while (n) ob[i++] = n%10 + '0', n/=10;
		while (i--) pc(ob[i]);
	}
	pc('\n');
}

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 k) {
	int a;
#if 0
	a = answer(y);
#else
	pc('?'), out(y), fflush(stdout);
	a = in();
#endif
	if (a == 0) {
		pc('!'), out(y+k);
		exit(0);
	}
	return a;
}

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

	m = 100, k = 0;
	a = ask(m, k++);
	if (a > 0) l = m, r = 1000000001;
	else l = 9, r = m-1;
	while (l < r) {
        m = (l + r) >> 1;
		a = ask(m, k++);
	    if (a > 0) l = m, r--;
		else l--, r = m-1;
	}
	pc('!'), out(l+k), fflush(stdout);
	return 0;
}