#include <bits/stdc++.h>
#define ll long long
#define pii pair <int, int>
#define fi first
#define se second
#define pb push_back
#define ull unsigned long long

using namespace std;
mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());
const int N = 1e6+5, mod = 998244353; 
int n, tot, k, f[N], id[N]; 
map <int, int> ch[N]; 
vector <int> las[N]; 
ll lv[26];  
int pre[26]; 
struct trie {
	int rt;  
	ll sm, sn; 
	void ins (string s, int l) {
		int p = rt;
		memset(pre, -1, sizeof pre);  
		for (int i = l;i < s.size();i++) {
			int x; 
			if (~pre[s[i]-'a']) {
				x = i-pre[s[i]-'a']; 
			}
			else x = 0; 
			pre[s[i]-'a'] = i; 
			if (ch[p].count(x)) p = ch[p][x]; 
			else {
				ch[p][x] = ++tot; p = tot; 
			}
		}
	}
	void dfs (int p, int x) {
		(sm += lv[x]) %= mod;
		if (!ch[p].count(0)) (sn += lv[x]*(k-ch[p].size()))%mod;  
		else (sn += lv[x]*(x+1-ch[p].size()))%mod; 
//		cout << p << " " << x << " " << endl; 
		for (auto i : ch[p]) dfs(i.se, x+(i.fi == 0)); 
	}
}tr[N];

string str; 
void solve () {
	cin >> n >> k; 
	lv[0] = 1; for (int i = 1;i < k;i++) lv[i] = lv[i-1]*(k-i)%mod; 	
	for (int i = 1;i <= n;i++) {
		int las = tot; 
		tr[i].rt = ++tot; 
		cin >> str; 
		for (int j = 0;j < str.size();j++) tr[i].ins(str, j); 
		tr[i].dfs(tr[i].rt+1, 0); 
	}
//	cout << "CASE\n"; 
	ll s = k, ans = 0; 
	for (int i = 1;i <= n;i++) {
		(ans += s*tr[i].sm) %= mod; 
//		cout << s << " " << tr[i].sm << endl;  
		s = s*tr[i].sn%mod;  
	}
	cout << (ans+1)%mod; 
}

signed main () {
//	ios::sync_with_stdio(0);
//	cin.tie(0); cout.tie(0);
	int T = 1;
	while (T--) solve();
	return 0;
}