Problem: One day Kefa found n baloons. For convenience, we denote color of i-th baloon as si — lowercase letter of the Latin alphabet. Also Kefa has k friends. Friend will be upset, If he get two baloons of the same color. Kefa want to give out all baloons to his friends. Help Kefa to find out, can he give out all his baloons, such that no one of his friens will be upset — print «YES», if he can, and «NO», otherwise. Note, that Kefa's friend will not upset, if he doesn't get baloons at all.

Input

The first line contains two integers n and k (1 ≤ n, k ≤ 100) — the number of baloons and friends.

Next line contains string s — colors of baloons.

Output

Answer to the task — «YES» or «NO» in a single line.

You can choose the case (lower or upper) for each letter arbitrary.

Examples

Input

4 2
aabb


Output

YES


Input

6 3
aacaab


Output

NO

Note

In the first sample Kefa can give 1-st and 3-rd baloon to the first friend, and 2-nd and 4-th to the second.

In the second sample Kefa needs to give to all his friends baloons of color a, but one baloon will stay, thats why answer is «NO».

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
clock_t time_p = clock();
void shahil_005() {
  time_p = clock() - time_p;
  cerr << "Time Taken : " << (float)(time_p) / CLOCKS_PER_SEC << "\n";
}
int power(long long x, long long y) {
  if (y == 0) return 1;
  long long p = power(x, y / 2);
  p = (p * p);
  return (y % 2 == 0) ? p : (x * p);
}
int lcm(long long a, long long b) {
  long long lar = max(a, b);
  long long small = min(a, b);
  for (long long i = lar;; i += lar) {
    if (i % small == 0) return i;
  }
}
int gcd(long long a, long long b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
int bsearch(long long arr[], long long l, long long r, long long x) {
  while (l <= r) {
    long long m = l + (r - l) / 2;
    if (arr[m] == x) {
      return m;
    }
    if (arr[m] < x) {
      l = m + 1;
    } else
      r = m - 1;
  }
  return -1;
}
bool prime(long long n) {
  if (n <= 1) return false;
  if (n <= 3) return true;
  if (n % 2 == 0 || n % 3 == 0) return false;
  for (int i = 5; i * i <= n; i = i + 6)
    if (n % i == 0 || n % (i + 2) == 0) return false;
  return true;
}
bool sortbysec(const pair<long long, long long> &a,
               const pair<long long, long long> &b) {
  return (a.second < b.second);
}
bool sortbydec(const pair<long long, long long> &a,
               const pair<long long, long long> &b) {
  return a.first > b.first;
}
const int N = 1e5 + 5;
const long long MOD = (long long)(1e9 + 7);
const long long INIT = (long long)(1e6 + 1);
long long a[26];
void solve() {
  long long n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  long long siz = s.size();
  for (long long i = 0; i < n; i++) {
    a[s[i] - 'a']++;
  }
  long long flag = 0;
  for (long long i = 0; i < 26; i++) {
    if (a[i] > k) {
      cout << "NO";
      flag = 1;
      break;
    }
  }
  long long xxx = 1;
  if (flag == 0) {
    cout << "YES";
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long t = 1;
  while (t--) {
    solve();
  }
  return 0;
}