#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <algorithm>
#include <cmath>
#include <vector>
#include <set>
#include <map>
#include <stdlib.h>
#include <stack>
#include <queue>
#define ri register int

inline int read() {
	int x=0,f=1;char ch=getchar();
	while(ch<'0'||ch>'9') {if(ch=='-')f=-1;ch=getchar();}
	while(ch>='0'&&ch<='9') {x=(x<<1)+(x<<3)+(ch^48);ch=getchar();}
	return x*f;
}

void write(int x){
  if(x>9) write(x/10);
  putchar(x%10^48);
}

void Clear(){fflush(stdout);}

int query(int l,int r){
	printf("? %d %d\n",l,r),Clear();
	int k=read();
	return k;
}

int main(){
	int n=read(),l=1,r=n,ans;
	int mex=query(1,n);
	if(mex==1||query(1,mex)!=mex){
		l=mex+1;
		while(l<=r){
//			if(l==r){printf("! %d\n",l),Clear(),exit(0);} 
			int mid=l+r>>1;
			int ls=query(mex,mid);
			if(ls==mex)r=mid-1,ans=mid;
			else l=mid+1;
		}
	}
	else {
		r=mex-1;
		while(l<=r){
//			if(l==r){printf("! %d\n",r),Clear(),exit(0);} 
			int mid=l+r>>1;
			int ls=query(mid,mex);
			if(ls==mex)l=mid+1,ans=mid;
			else r=mid-1;
		}
	}
	printf("! %d\n",ans),Clear();
	return 0;
}
