#include <bits/stdc++.h>
using namespace std;

int main()
{
    int H, W;
    cin >> H >> W;
    vector<string> a(H);
    vector<int> num(26, 0);
    for (int i = 0; i < H; ++i) {
        cin >> a[i];
        for (char c : a[i]) {
            num[c - 'a']++;
        }
    }
    int odd_num = 0, num4 = 0;
    for (int i = 0; i < 26; ++i) {
        num4 += num[i] / 4;
        if (num[i] % 2 == 1) {
            odd_num++;
        }
    }

    int h = (H % 2 == 0 ? H / 2 : (H - 1) / 2);
    int w = (W % 2 == 0 ? W / 2 : (W - 1) / 2);

    if (odd_num == (H % 2 == 1 && W % 2 == 1)
            && h * w <= num4)
        cout << "Yes" << endl;
    else
        cout << "No" << endl;

    return 0;
}