#include <bits/stdc++.h>

using namespace std;

string s;
int k, odds;
int cnt[5000];
main() {
    cin >> s >> k;
    int n = s.size();
    for(int i = 0; i < s.size(); i++)
        cnt[s[i] - 'a']++;
    for(int i = 0; i < 26; i++)
        odds += cnt[i]%2;
    if(odds <= k + 1)
        cout << "YES\n";
    else cout << "NO\n";
}