#include <iostream>

int q(int x)
{
    int ret;
    
    std::cout << "? " << x << std::endl;
    std::cout << std::flush;
    
    std::cin >> ret;
    return ret;
}

int main()
{
    int a;
    a = q(100);
    
    if(a == 0)
    {
        std::cout << "! 100" << std::endl;
        return 0;
    }
    
    int min, max, cur, i;
    min = 1;
    max = (a > 0)? 1000000000:100;
    cur = (max - min) / 2;
    i = 1;
    
    int p = 100, pp = -1;
    
    for(; i < 100; i++)
    {
        a = q(cur);
        if(a == 0)
            break;
        
        pp = p;
        p = cur;
        
        if(a > 0)
        {
            min = cur + 1;
            cur += ((max - min) / 2);
        }
        else
        {
            max = cur - 1;
            cur -= ((max - min) / 2) - 1;
        }
        
        if(cur == (p - 1) && cur == (pp - 2))
            cur--;

        max--;
        min--;
    }
    
    std::cout << "! " << cur + i << std::endl;
    
    return 0;
}