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

const int N = 1e3 + 5;
int sum[30], s[5];

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++) sum[S[j] - 'a']++;
	}
	for (int i = 0; i < 26; i++)
	{
		s[4] += sum[i] / 4;
		sum[i] %= 4;
		s[2] += sum[i] / 2;
		s[1] += sum[i] % 2;
	}
	int a = 0, b = 0, c = 0;
	a = (n / 2) * (m / 2);
	if (n & 1) b += m / 2;
	if (m & 1) b += n / 2;
	if (n % 2 && m % 2) c = 1;
//	cout << a << " " << b << " " << c << endl;
	int ans = 1;
	if (s[4] < a) ans = 0;
	s[4] -= a; s[2] += s[4] * 2;
	if (s[2] < b) ans = 0;
	s[2] -= b; s[1] += s[2] * 2;
	if (s[1] < c) ans = 0;
	puts(ans ? "Yes" : "No");
	return 0;
}