using System;
using System.Collections.Generic;
using System.Linq;
using static System.Console;
using static System.Math;

class MainClass : Scanner
{
    static void Main()
    {
        var (H, W) = ReadStream<int,int>();
        var dic = new Dictionary<char, int>();
        for (int i = 0; i < H; i++)
        {
            var line = RString();
            for (int j = 0; j < W; j++)
            {
                if (!dic.ContainsKey(line[j])) dic[line[j]] = 1;
                else dic[line[j]]++;
            }
        }
        bool frag = true;
        if (H % 2 == 0 && W % 2 == 0)
        {
            foreach (var item in dic.Values)
            {
                if (item % 4 > 0) frag = false;
            }

        }
        else if (H % 2 == 0 || W % 2 == 0)
        {
            int even = 0;
            if (H % 2 == 0) even = H;
            else even = W;

            int cnt2 = 0;
            int cnt4 = 0;
            foreach (var item in dic.Values)
            {
                if (item % 2 > 0) frag = false;
                else if (item % 4 > 0) cnt2++;
                else cnt4++;
            }
            if (cnt2 > even / 2) frag = false;
        }
        else
        {
            int even = (W - 1) / 2 + (H - 1) / 2;
            int cnt1 = 0;
            int cnt2 = 0;
            foreach (var item in dic.Values)
            {
                if (item % 2 > 0) cnt1++;
                else if (item % 4 > 0) cnt2++;
            }
            if (cnt1 > 1) frag = false;
            else if (cnt2 > even) frag = false;
        }
        WriteLine(frag?"Yes":"No");
    }
}



class Scanner
{
    public static int RInt() => int.Parse(Console.ReadLine());
    public static long RLong() => long.Parse(Console.ReadLine());
    public static string RString() => Console.ReadLine();
    public static double RDouble() => double.Parse(Console.ReadLine());

    public static int[] RInts() => Array.ConvertAll(Console.ReadLine().Split(), int.Parse);
    public static int[] RInts(Func<string, int> func) => Console.ReadLine().Split().Select(func).ToArray();
    public static long[] RLongs() => Array.ConvertAll(Console.ReadLine().Split(), long.Parse);
    public static long[] RLongs(Func<string, long> func) => Console.ReadLine().Split().Select(func).ToArray();
    public static double[] RDoubles() => Array.ConvertAll(Console.ReadLine().Split(), double.Parse);
    public static double[] RDoubles(Func<string, double> func) => Console.ReadLine().Split().Select(func).ToArray();
    public static string[] RStrings() => Console.ReadLine().Split();
    //public static string[] RStrings(Func<string, string> func) => Console.ReadLine().Split().Select(func).ToArray();
    public static T1 ReadStream<T1>()
    {
        var r = RStrings();
        var r1 = (T1)Convert.ChangeType(r[0], typeof(T1));
        return r1;
    }
    public static (T1, T2) ReadStream<T1, T2>()
    {
        var r = RStrings();
        var r1 = (T1)Convert.ChangeType(r[0], typeof(T1));
        var r2 = (T2)Convert.ChangeType(r[1], typeof(T2));
        return (r1, r2);
    }
    public static (T1, T2, T3) ReadStream<T1, T2, T3>()
    {
        var r = RStrings();
        var r1 = (T1)Convert.ChangeType(r[0], typeof(T1));
        var r2 = (T2)Convert.ChangeType(r[1], typeof(T2));
        var r3 = (T3)Convert.ChangeType(r[2], typeof(T3));
        return (r1, r2, r3);
    }
    public static (T1, T2, T3, T4) ReadStream<T1, T2, T3, T4>()
    {
        var r = RStrings();
        var r1 = (T1)Convert.ChangeType(r[0], typeof(T1));
        var r2 = (T2)Convert.ChangeType(r[1], typeof(T2));
        var r3 = (T3)Convert.ChangeType(r[2], typeof(T3));
        var r4 = (T4)Convert.ChangeType(r[3], typeof(T4));
        return (r1, r2, r3, r4);
    }
}

Measured memory_bytes: 27976