import java.io.*;
import java.util.*;

public class Main {
    static ContestScanner in;
    static Writer out;
    public static void main(String[] args) {
        Main main = new Main();
        try {
            in = new ContestScanner();
            out = new Writer();
            main.solve();
            out.close();
            in.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    void solve() throws IOException {
        int h = in.nextInt();
        int w = in.nextInt();
        char[][] map = new char[h][];
        int[] alp = new int[26];
        for (int i = 0; i < h; i++) {
            map[i] = in.nextToken().toCharArray();
            for (int j = 0; j < w; j++) {
                alp[map[i][j] - 'a']++;
            }
        }
        int four = (h/2) * (w/2);
        int one = h % 2 == 1 && w % 2 == 1 ? 1 : 0;
        int two = (h % 2) * (w / 2) + (w % 2) * (h / 2);
        for (int i = 0; i < 26; i++) {
            int minus = Math.min(alp[i] / 4, four);
            four -= minus;
            alp[i] -= minus * 4;
        }

        for (int i = 0; i < 26; i++) {
            int minus = Math.min(alp[i] / 2, two);
            two -= minus;
            alp[i] -= minus * 2;
        }

        for (int i = 0; i < 26; i++) {
            int minus = Math.min(alp[i], one);
            one -= minus;
            alp[i] -= minus * 1;
        }

        if(four == 0 && two == 0 && one == 0) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
    }

}

@SuppressWarnings("serial")
class MultiSet<T> extends HashMap<T, Long>{
    @Override public Long get(Object key){return containsKey(key)?super.get(key):0L;}
    public void add(T key,long v){put(key,get(key)+v);}
    public void add(T key){put(key,get(key)+1);}
    public void sub(T key){final long v=get(key);if(v==1)remove(key);else put(key,v-1);}
    public MultiSet<T> merge(MultiSet<T> set)
    {MultiSet<T>s,l;if(this.size()<set.size()){s=this;l=set;}else{s=set;l=this;}
        for(Entry<T,Long>e:s.entrySet())l.add(e.getKey(),e.getValue());return l;}
}

class Writer extends PrintWriter{
    public Writer(String filename)throws IOException
    {super(new BufferedWriter(new FileWriter(filename)));}
    public Writer()throws IOException{super(System.out);}
}
class ContestScanner implements Closeable{
    private BufferedReader in;private int c=-2;
    public ContestScanner()throws IOException
    {in=new BufferedReader(new InputStreamReader(System.in));}
    public ContestScanner(String filename)throws IOException
    {in=new BufferedReader(new InputStreamReader(new FileInputStream(filename)));}
    public String nextToken()throws IOException {
        StringBuilder sb=new StringBuilder();
        while((c=in.read())!=-1&&Character.isWhitespace(c));
        while(c!=-1&&!Character.isWhitespace(c)){sb.append((char)c);c=in.read();}
        return sb.toString();
    }
    public String readLine()throws IOException{
        StringBuilder sb=new StringBuilder();if(c==-2)c=in.read();
        while(c!=-1&&c!='\n'&&c!='\r'){sb.append((char)c);c=in.read();}
        return sb.toString();
    }
    public long nextLong()throws IOException,NumberFormatException
    {return Long.parseLong(nextToken());}
    public int nextInt()throws NumberFormatException,IOException
    {return(int)nextLong();}
    public double nextDouble()throws NumberFormatException,IOException
    {return Double.parseDouble(nextToken());}
    public void close() throws IOException {in.close();}
}


Measured memory_bytes: 23508