#include <bits/stdc++.h>
using namespace std;
using Int = long long;
constexpr static int mod = 1e9 + 7;
constexpr static int inf = (1 << 30) - 1;
constexpr static Int infll = (1LL << 61) - 1;
int Competitive_Programming = (ios_base::sync_with_stdio(false), cin.tie(nullptr), cout << fixed << setprecision(15), 0);

int enc(string s)
{
	int ret = 0;
	for (int i = 0; i < s.size(); i++)
		ret *= 4, ret += s[i] - 'A';
	return ret;
}

int dfs(string &s, map<string, int> &dp, map<string, int> &mp, map<string, int> &used)
{
	if (dp.find(s) != dp.end())
	{
		int ret = (used[s] ? 0 : dp[s] + mp[s]);
		used[s] = 1;
		return ret;
	}

	int ret = 0;

	for (int i = 0; i < s.size(); i++)
	{
		if (s[i] == 'D')
			continue;
		s[i]++;
		ret += dfs(s, dp, mp, used);
		if (used[s] == 0 and mp[s] == 1)
			ret++;
		used[s] = 1;
		s[i]--;
	}

	return dp[s] = ret;
}

int main()
{
	int N, K;
	cin >> N >> K;
	vector<string> s(N);
	map<string, int> mp, used, dp;

	for (int i = 0; i < N; i++)
	{
		cin >> s[i];
		mp[s[i]]++;
	}

	int ans = 0;

	for (int i = 0; i < N; i++)
	{
		ans += dfs(s[i], dp, mp, used);
		dp[s[i]] = 0;
	}

	cout << ans << '\n';
}