#include <iostream>
#include <algorithm>

using namespace std;

typedef long long ll;

int main()
{

    int l=1,r=1000000000;
    int ans,rez;
    while(l<=r){
        int mid=(l+r)/2;
        cout<<"? "<<mid<<endl;
        cin>>ans;
        if(ans==1){
            rez=mid;
            l=mid+1;
        }
        else{
            r=mid-1;
        }
    }
    cout<<"! "<<rez;
    return 0;
}