#include <bits/stdc++.h>
using namespace std;

int main() {
	int arr[]={1, 2, 3, 1, 4, 5};
	int n=sizeof(arr)/sizeof(arr[0]);
	int k=3;
	bool flag=false;
	unordered_map<int, int> mp;
	for(int i=0;i<n;i++){
		if(mp.find(arr[i])!=mp.end()){
			if(i - mp[arr[i]] <= k) {
                flag = true;
                cout << "yes";
                break;
            }
		}
		mp[arr[i]]=i;
	}
	if(flag==false)
		cout<<"no";
	return 0;
}