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 JAVA):

Solution:
import javax.print.DocFlavor;
import java.io.*;
import java.util.*;

public class Main {
    static final boolean ONLINE_JUDGE = System.getProperty("ONLINE_JUDGE") != null;
    static final int[][] STEPS = {{1, 0}, {0, 1}, {-1, 0}, {0, -1}};

    boolean checkIndex(int index, int size) {
        return (0 <= index && index < size);
    }

    int abs(int a) {
        return Math.abs(a);
    }


    // ======================================================
    void solve() throws IOException {
        int n = readInt();
        int k = readInt();
        HashMap<Character, Integer> set = new HashMap<Character, Integer>();
        String a = readString();
        for (int i = 0; i < a.length(); i++) {
            set.put(a.charAt(i), set.getOrDefault(a.charAt(i), 0) + 1);
        }

        for (int i = 0; i < n; i++) {
            if(set.get(a.charAt(i))<=k){
                continue;
            }
            else {
                out.println("NO");
                return;
            }
        }
        out.println("YES");
    }


    //=======================================================


    int[] merge(int[] a, int[] b) {
        int[] c = new int[a.length + b.length];
        int ai = 0, i = 0, bi = 0;
        while (ai < a.length || bi < b.length) {
            if (ai < a.length && bi < b.length) {
                if (a[ai] <= b[bi]) {
                    c[i] = a[ai];
                    ai++;
                } else {
                    c[i] = b[bi];
                    bi++;
                }
            } else {
                if (bi < b.length) {
                    c[i] = b[bi];
                    bi++;
                } else {
                    c[i] = a[ai];
                    ai++;
                }
            }
            i++;

        }
        return c;
    }


    int minInt(int... values) {
        int min = Integer.MAX_VALUE;
        for (int value : values) {
            min = Math.min(min, value);
        }
        return min;
    }

    int maxInt(int... values) {
        int max = Integer.MIN_VALUE;
        for (int value : values) {
            max = Math.max(max, value);
        }
        return max;
    }

    long minLong(long... values) {
        long min = Long.MAX_VALUE;
        for (long value : values) {
            min = Math.min(min, value);
        }
        return min;
    }

    long maxLong(long... values) {
        long max = Long.MIN_VALUE;
        for (long value : values) {
            max = Math.max(max, value);
        }
        return max;
    }

    public static void main(String[] args) {
        new Main().run();
    }

    BufferedReader in;
    PrintWriter out;
    StringTokenizer tok;


    void init() throws FileNotFoundException {
        if (ONLINE_JUDGE) {
            in = new BufferedReader(new InputStreamReader(System.in));
            out = new PrintWriter(System.out);
        } else {
            in = new BufferedReader(new FileReader("input.txt"));
            out = new PrintWriter("output.txt");
        }
        tok = new
                StringTokenizer("");
    }

    void run() {
        try {
            long timeStart = System.currentTimeMillis();

            init();
            solve();

            out.close();

            long timeEnd = System.currentTimeMillis();
            System.err.println("time = " + (timeEnd - timeStart) + " compiled");
        } catch (Exception e) {
            e.printStackTrace();
            System.exit(-1);
        }


    }

    String readLine() throws IOException {
        return in.readLine();
    }

    String delimiter = " ";

    String readString() throws IOException {
        while (!tok.hasMoreTokens()) {
            String nextLine = readLine();
            if (null == nextLine)
                return null;

            tok = new StringTokenizer(nextLine);
        }

        return tok.nextToken(delimiter);
    }

    int[] readIntArray(int b) {
        int a[] = new int[b];
        for (int i = 0; i < b; i++) {
            try {
                a[i] = readInt();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return a;
    }

    long[] readLongArray(int b) {
        long a[] = new long[b];
        for (int i = 0; i < b; i++) {
            try {
                a[i] = readLong();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return a;
    }

    int readInt() throws IOException {
        return Integer.parseInt(readString());
    }

    long readLong() throws IOException {
        return Long.parseLong(readString());
    }


    void sortArrayInt(int[] a) {
        Integer arr[] = new Integer[a.length];
        for (int i = 0; i < a.length; i++) {
            arr[i] = a[i];
        }
        Arrays.sort(arr);
        for (int i = 0; i < a.length; i++) {
            a[i] = arr[i];
        }
    }

    void sortArrayLong(long[] a) {
        Long arr[] = new Long[a.length];
        for (int i = 0; i < a.length; i++) {
            arr[i] = a[i];
        }
        Arrays.sort(arr);
        for (int i = 0; i < a.length; i++) {
            a[i] = arr[i];
        }
    }


}