#include <iostream>

int ask(int n){
    std::cout << "? " << n << std::endl;
    int res = 0;
    std::cin >> res;
    return res;
}

void answer(int n){
    std::cout << "! " << n << std::endl;
}

int main(){
    int lb = 10, ub = 1000000001;
    int res;
    
    std::cout << "? 100" << std::endl;
    std::cin >> res;

    if(res == 0){
        answer(res);
        return 0;
    }else if(res == -1){
        for(int i=1;i<100;i++){
            res = ask(0);
            if(res == 0){
                answer(i);
                return 0;
            }
        }
    }else{
        for(int i=0;i<100;i++){
            int mid = (lb + ub) / 2;
            std::cout << "? " << mid << std::endl;
            int res;
            std::cin >> res;
            if(res == 0){
                std::cout << "! " << (mid + i) << std::endl;
                return 0;
            }else if(res == 1){
                lb = mid;
            }else{
                ub = mid;
            }

            lb = std::max(0, lb-1);
            ub = ub - 1;
        }

    }
}