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

int main() {
	
	int n,k;
	cin>>n>>k;
	
	vector<int> numbers(n);
	
	for(auto& number: numbers){
		cin>>number;
	}
	
	unordered_map<int,int> lastIndex;
	
	bool answer = false;
	
	for(int i=0; i<n; i++){
		if(lastIndex.find(numbers[i]) != lastIndex.end()){
			if( i - lastIndex[numbers[i]] <= k ){
				answer = true;
				break;
			}
			
			
		}
		
		lastIndex[numbers[i]] = i;
		
	}
	
	(answer == true)?(cout<<"yes"):(cout<<"no");
	
	return 0;
}