import std.stdio, std.string, std.conv;
import std.range, std.algorithm, std.array, std.math;


void main() {
    int h, w;
    scan(h, w);

    auto ban = new char[][](h, w);
    iota(h).each!(i => ban[i] = readln.chomp.to!(char[]));

    auto cnt = new int[](26);
    foreach (i ; 0 .. h) {
        foreach (j ; 0 .. w) {
            cnt[ban[i][j] - 'a']++;
        }
    }

    if (h & 1) swap(h, w);

    auto odd = cnt.count!"a % 2 == 1".to!int;
    auto even = cnt.count!"a % 2 == 0 && a % 4 != 0".to!int;
    auto m4 = cnt.count!"a % 4 == 0".to!int;

    bool ok;

    if ((h & 1) && (w & 1)) {
        if (odd == 1 && even <= (h / 2 + w / 2)) {
            ok = 1;
        }
    }
    else if (w & 1) {
        if (odd == 0 && even <= (h / 2)) {
            ok = 1;
        }
    }
    else {
        if (odd == 0 && even == 0) {
            ok = 1;
        }
    }

    writeln(ok ? "Yes" : "No");
}



void scan(T...)(ref T args) {
    import std.stdio : readln;
    import std.algorithm : splitter;
    import std.conv : to;
    import std.range.primitives;

    auto line = readln().splitter();
    foreach (ref arg; args) {
        arg = line.front.to!(typeof(arg));
        line.popFront();
    }
    assert(line.empty);
}



void fillAll(R, T)(ref R arr, T value) {
    static if (is(typeof(arr[] = value))) {
        arr[] = value;
    }
    else {
        foreach (ref e; arr) {
            fillAll(e, value);
        }
    }
}
