#include <bits/stdc++.h>
//#include <atcoder/all>
using namespace std;
//using namespace atcoder;
typedef long long ll;
typedef pair<ll,ll> P;
//typedef modint998244353 mint;
ll n;
string s;
int main(void){
    cin.tie(0);
    ios::sync_with_stdio(0);
    cin>>n>>s;
    if(n>=4){
        cout<<"YES"<<endl;
    }else if(n==3){
        for(int i=0;i<3;i++){
            if(s[i]==s[i+1]){
                cout<<"YES"<<endl;
                return 0;
            }
        }
        cout<<"NO"<<endl;
    }else if(n==2){
        if(s=="00"||s=="11"){
            cout<<"YES"<<endl;
        }else{
            cout<<"NO"<<endl;
        }
    }else{
        cout<<"NO"<<endl;
    }

}