#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
#define fi first
#define se second
#define vi vector<int>
#define vll vector<long long>
#define pii pair<int, int>
#define pll pair<long long, long long>
#define pb push_back
#define mp make_pair
#define eb emplace_back
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
mt19937_64 rng64(chrono::high_resolution_clock::now().time_since_epoch().count());
inline int rand(int l,int r){return uniform_int_distribution<int>(l, r)(rng);}
inline ll rand(ll l,ll r){return uniform_int_distribution<ll>(l, r)(rng64);}
#ifdef DEBUG
auto&operator<<(auto&o,pair<auto,auto>p){return o<<"("<<p.first<<", "<<p.second<<")";}
auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{";int i=0;for(auto e:x)o<<","+!i++<<e;return o<<"}";}
#define debug(X...)cerr<<"["#X"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(X)
#else
#define debug(...){}
#endif
struct custom_hash {
static uint64_t splitmix64(uint64_t x) {
x += 0x9e3779b97f4a7c15;
x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
return x ^ (x >> 31);
}
size_t operator()(uint64_t x) const {
static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
return splitmix64(x + FIXED_RANDOM);
}
};
struct pair_hash{
size_t operator()(const pair<int,int>&x)const{
return hash<long long>()(((long long)x.first)^(((long long)x.second)<<32));
}
};
int ask(ll k){
cout << "? " << k << endl;
int res;
cin >> res;
return res;
}
int main(){
/*ios_base::sync_with_stdio(0);
cin.tie(NULL);
cout.tie(NULL);*/
ll n;
cin >> n;
ll C = 0LL;
int B = 0;
for(int k = 60; k >= 0; k--){
if((1LL << k) > n){
continue;
}
B = k;
break;
}
ask((1LL << B));
if(!ask(1)){
C += (1LL << B);
}
ll l = 1LL;
for(int k = B - 1; k >= 0; k--){
if((1LL << k) + C > n){
continue;
}
ll val = (1LL << k) + C;
if(val == (1LL << B)){
ask(val + 1);
if(!ask(2)){
C++;
}
}else{
if(!ask(val)){
C += (1LL << k);
}
}
}
cout << "= " << C << endl;
return 0;
}
