#include <iostream>
using namespace std;
int main(void){
    long long min=1,max=1000000000;
    while(true){
        cout<<"? "<<(min+max+1)/2<<endl;
        int a;
        cin>>a;
        if(a==1){
            min=(min+max+1)/2;
        }else{
            max=(min+max+1)/2-1;
        }
        if(min==max){
            cout<<"! "<<min<<endl;
            break;
        }
    }
    return 0;
}