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

void executeTime() {
    cerr << "Time Taken: " << (float)clock() / CLOCKS_PER_SEC << " secs";
}

int main() {

    int n, k; cin >> n >> k;

    vector<int> v(n);
    for (auto &x : v) {
        cin >> x;
    }

    unordered_map<int, int> mp;
    int f = 1;

    for (int i = 0; i < n; i++) {
        if (mp.count(v[i])) {
            if (i - mp[v[i]] <= k) {
                f = 0;
                cout << "YES" << endl;
                break;
            }
        }

        mp[v[i]] = i;
    }

    if (f) cout << "NO" << endl;

    executeTime();
    return 0;
}