#include<bits/stdc++.h>
using namespace std;
 
bool cst(char a,char b){
	if(a<=b) return true;
	else return false;
}
 
string unlucky(char str[],int n){
	int ptr1=0,ptr2=n,x;
	if(str[ptr1]>str[ptr2]) x=1;
	else x=0;
	while(ptr1<n && ptr2<(2*n)){
		if(x==1 && str[ptr1]<=str[ptr2]) return "NO";
		else if(x==0 && str[ptr1]>=str[ptr2]) return "NO";
		ptr1++;
		ptr2++;
	}
	return "YES";
}
 
int main(){
	int n;
	string str;
	cin>>n>>str;
	char v[2*n];
	for(int i=0;i<2*n;i++) v[i]=str[i];
	sort(v,v+n,cst);
	sort(v+n,v+(2*n),cst);
	cout<<unlucky(v,n);
	return 0;
}

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NTAKMDAxMzAxMTIwMTExMTExMjIxMDIzMTMzMzEyMTAzMDAzMTAyMTEzMjMyMzIzMjMyMjMzMTQyMjI1MzIxNTMxMjQ1NDQzMTMxMjI1MjQ1NDUzMTEyMTMyNTE1NDMzMjQ1MjUyMg==

50
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