#include <iostream>
#include <algorithm>
#include <stdlib.h>
#include <string>
using namespace std;






int main() {
int n,ans;
string s;

cin>>n;
cin>>s;
if(n>3) ans=1;
if(n==3){
if(s=="000" ||s=="001" ||s=="011" ||s=="100" ||s=="110" ||s=="111") ans =1;
else ans= 0;
}
if(n==2){
if(s=="00" || s=="11") ans=1;
else ans=0;
}
if(n==1) ans=0;

if(ans==0) cout<<"NO"<<endl;
else cout<<"YES"<<endl;
	return 0;
}