#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#define df 0

int i=1<<30;
int s=0;
void ask(){
  printf("? %d\n",s+i);
  fflush(stdout);
  int flag;
  scanf("%d",&flag);
  if(flag) s+=i;
}

int main(){
  while(i){
    ask();
    i>>=1;
  }
  printf("! %d\n",s);
  return 0;
}


/// confirm df==0 ///