#include<stdio.h>

void run(void){

  int l=1;
  int h=1000000001;

  while(l+1<h){
    int m=(l+h)/2;
    printf("? %d\n",m);
    fflush(stdout);
    int d;
    scanf("%d",&d);
    if(d==0){
      h=m;
    } else {
      l=m;
    }
  }
  printf("! %d\n",l);
  return;
}

int main(void){
  run();
  return 0;
}