#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <string>
#include <cmath>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <cstring>

typedef long long ll;
using namespace std;

#define mod 1000000007
#define INF 1000000000
#define LLINF 2000000000000000000LL

#define MAX_L 5000000
#define SIZE 1000000

int main(){
    int l,r,in;
    
    l=1;
    r=1000000000;
    
    while(l<r){
        
        printf("? %d\n",(l+r+1)/2);
        fflush(stdout);
        
        scanf("%d",&in);
        
        if(in==1){
            l = (l+r+1)/2;
        }else{
            r = (l+r+1)/2 -1;
        }
        
    }
    
    printf("! %d\n",l);
    
    return 0;
}