#include <iostream>
using namespace std;
int main()
{
    int L=0, R=2000000000;
    while (R-L>1) {
        int M=(L+R)/2;
        cout<<"? "<<M<<endl;
        int in;
        cin>>in;
        if (in)
            R=M/2;
        else
            L=M/2;
    }
    cout<<"! "<<L<<endl;
}