import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.io.StreamTokenizer;
public class Colors {
static StreamTokenizer in;
static PrintWriter out;
static int nextInt() throws IOException {
in.nextToken();
return Integer.parseInt(in.sval);
}
static long nextLong() throws IOException {
in.nextToken();
return Long.parseLong(in.sval);
}
static long n;
static long last;
static long plast;
static int lastAnswer;
static int ask(long x) throws IOException {
out.print("? ");
out.println(x);
out.flush();
int v = nextInt();
return v;
}
static void ask4(long x) throws IOException {
plast = last;
last = x;
lastAnswer = ask(x);
}
static void giveAnswer(long x) {
out.print("= ");
out.println(x);
out.flush();
}
static long mas[] = new long[70];
public static void main(String[] args) throws IOException {
in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
out = new PrintWriter(System.out);
in.resetSyntax();
in.whitespaceChars(0, 32);
in.wordChars('0', '9');
in.wordChars('-', '-');
n = nextLong();
int i = 0;
mas[0] = n;
if (mas[0] > 2) {
while (mas[i] > 4) {
i++;
mas[i] = mas[i - 1] / 2 + mas[i - 1] % 2;
}
boolean aug = true;
long f = 2;
for (int j = i - 1; j >= 0; j--) {
aug = !aug;
if (!aug) {
f = mas[j] + f - mas[j + 1];
}
}
long add1 = 0;
long add2 = 0;
ask4(f);
for (int j = 0; j < i; j++) {
long g = mas[j] - mas[j + 1] + add2;
if (aug) {
ask4(last + g);
} else {
ask4(last - g);
}
// if (lastAnswer && aug)
// {
// add1 += g;
// }
if (lastAnswer == 0) {
add2 += mas[j] - mas[j + 1];
}
aug = !aug;
}
if (mas[i] == 3) {
ask4(last + add2 + 1);
if (lastAnswer == 0) {
ask4(last - add2 - 2);
if (lastAnswer > 0) {
giveAnswer(add2 + 2);
} else {
giveAnswer(add2 + 3);
}
} else {
giveAnswer(add2 + 1);
}
} else if (mas[i] == 4) {
ask4(last + add2 + 2);
if (lastAnswer > 0) {
ask4(last - add2 - 1);
if (lastAnswer > 0) {
giveAnswer(add2 + 1);
} else {
giveAnswer(add2 + 2);
}
} else {
ask4(last - add2 - 3);
if (lastAnswer > 0) {
giveAnswer(add2 + 3);
} else {
giveAnswer((add2 + 4));
}
}
}
} else {
ask4(1);
ask4(2);
if (lastAnswer > 0) {
giveAnswer(1);
} else {
giveAnswer(2);
}
}
}
}
