#include <cstdio>
#include <iostream>
#include <cstring>

typedef long long LL;

#define L int(1e6 + 5)
#define P LL(1e9 + 7)

using namespace std;

char s[L];
LL hash[L], a[L], p[L];
int t, k;

LL count_hash(int l, int r) {
    if (!l) return hash[r];
    return hash[r] - hash[l - 1] * p[r - l + 1];
}

int main() {
    freopen("autoreg.in", "r", stdin);
    freopen("autoreg.out", "w", stdout);

    gets(s);
    int l = strlen(s);
    scanf("%d", &k);

    hash[0] = s[0];
    for (int i = 1; i < l; i++)
        hash[i] = hash[i - 1] * P + s[i];

    p[0] = 1;
    for (int i = 1; i < l; i++)
        p[i] = p[i - 1] * P;

    for (int i = k - 1; i < l; i++) {
        a[t++] = count_hash(i - k + 1, i);
    }

    sort(a, a + t);

    for (int i = 1; i < t; i++)
        if (a[i] == a[i - 1]) {
            puts("YES");
            return 0;
        }

    puts("NO");

    return 0;
}