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

// dfmt off
T lread(T = long)(){return readln.chomp.to!T();}
T[] aryread(T = long)(){return readln.split.to!(T[])();}
void scan(TList...)(ref TList Args){auto line = readln.split();
foreach (i, T; TList){T val = line[i].to!(T);Args[i] = val;}}
alias sread = () => readln.chomp();enum MOD = 10 ^^ 9 + 7;
alias PQueue(T, alias less = "a<b") = BinaryHeap!(Array!T, less);
// dfmt on

void main()
{
    long H, W;
    scan(H, W);
    auto cnt = new long[]('z' - 'a' + 1);
    foreach (_; 0 .. H)
        foreach (c; sread())
            cnt[c - 'a']++;
    long[] task;
    foreach (y; 0 .. (H + 1) / 2)
        foreach (x; 0 .. (W + 1) / 2)
        {
            long iy = H - y - 1;
            long ix = W - x - 1;
            task ~= () {
                if (y == iy && x == ix)
                    return 1;
                if (y == iy || x == ix)
                    return 2;
                return 4;
            }();
        }
    task.sort!"b<a"();
    outer: foreach (t; task)
    {
        foreach (i; 0 .. cnt.length)
            if (t <= cnt[i])
            {
                cnt[i] -= t;
                continue outer;
            }
        writeln("No");
        return;
    }
    writeln("Yes");
}
