import core.bitop, std.algorithm, std.ascii, std.bigint, std.conv,
    std.functional, std.math, std.numeric, std.range, std.stdio, std.string,
    std.random, std.typecons, std.container;

ulong MAX = 1_000_100, MOD = 1_000_000_007, INF = 1_000_000_000_000;
alias sread = () => readln.chomp();
alias lread(T = long) = () => readln.chomp.to!(T);
alias aryread(T = long) = () => readln.split.to!(T[]);
alias Pair = Tuple!(long, "p", long, "dist");
alias PQueue(T, alias less = "a<b") = BinaryHeap!(Array!T, less);

void main()
{
    long h, w;
    scan(h, w);
    auto alphabets = new long[](26);
    foreach (_; iota(h))
    {
        auto s = sread();
        foreach (e; s)
            alphabets[e - 'a']++;
    }
    long only, two, four;
    foreach (e; alphabets)
    {
        if (e % 2)
            only++;
        else if (e % 4)
            two++;
        else
            four++;
    }
    if (h % 2 && w % 2)
    {
        if (only == 1 && two <= h / 2 + w / 2)
            writeln("Yes");
        else
            writeln("No");
    }
    else if (h % 2)
    {
        if (only == 0 && two <= w / 2)
            writeln("Yes");
        else
            writeln("No");
    }
    else if (w % 2)
    {
        if (only == 0 && two <= h / 2)
            writeln("Yes");
        else
            writeln("No");
    }
    else
    {
        if (only == 0 && two == 0)
            writeln("Yes");
        else
            writeln("No");
    }

}

void scan(TList...)(ref TList Args)
{
    auto line = readln.split();
    foreach (i, T; TList)
    {
        T val = line[i].to!(T);
        Args[i] = val;
    }
}
