#include<bits/stdc++.h>
using namespace std;

int ask(int Y){
    printf("? %d\n",Y);
    fflush(stdout);
    int res;
    scanf("%d",&res);
    return res;
}

int main(){
    int ub,lb,cnt=1;
    if(ask(100)==-1){
        ub=100;
        lb=0;
    }
    else{
        ub=1e9;
        lb=0;
    }

    while(ub-lb>1){

        int mid=(ub+lb)/2;
        int r=ask(mid);
        if(r==1)lb=mid;
        else if(r==-1)ub=mid;
        else{
            printf("! %d\n",mid+cnt);
            fflush(stdout);
            return 0;
        }
        cnt++;
        ub--;
        lb--;
    }
    return 0;
}