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

int freq[26];

int main() {
	
	int n, m;

	cin >> n >> m;

	for (int i = 0; i < n; ++i)
	{
		string s;

		cin >> s;

		for (int j = 0; j < m; ++j)
		{
			freq[s[j] - 'a']++;
		}
	}

	int four = (n / 2) * (m / 2);
	int two = (n % 2) * (m / 2) + (m % 2) * (n / 2);
	int one = (n % 2) * (m % 2);

	for (int i = 0; i < 26; ++i)
	{
		int tmp = min(four, freq[i]/4);
		four -= tmp;
		freq[i] -= tmp*4;

		tmp = min(two, freq[i]/2);
		two -= tmp;
		freq[i] -= tmp*2;

		tmp = min(one, freq[i]/1);
		one -= tmp;
		freq[i] -= tmp*1;

		if (freq[i] > 0)
		{
			cout << "No";
			return 0;
		}
	}

	cout << "Yes";

	return 0;
}