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

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]; 
int pre[26]; 
struct trie {
	int rt; 
	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; 
			if (las[p].empty()) {
				for (int j = 0;j < k;j++) if (~pre[j]) las[p].pb(i-pre[j]); 
			}
//			cout << "INS:" << s << " " << l << " " << i << " " << p << " " << las[p].size() << " " << x << endl; 
			pre[s[i]-'a'] = i; 
			if (ch[p].count(x)) p = ch[p][x]; 
			else {
				ch[p][x] = ++tot; p = tot; 
			}
		}
	}
}tr[N];

string str; 
void solve () {
	cin >> n >> k; 
	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); 
		for (int j = las+1;j <= tot;j++) id[j] = i;  
//		cout << las+1 << " " << tot << endl; 
	}
	for (int i = 1;i <= tot;i++) las[i].pb(0); 
//	cout << "CASE\n"; 
	f[2] = k; int ans = 0; 
	for (int i = 2;i <= tot;i++) {
//		cout << i << " " << f[i] << endl; 
		for (int z : las[i]) {
			int v = z ? 1 : (k-las[i].size()+1); 
//			cout << i << " " << z << " " << v << endl; 
			if (ch[i].count(z)) (f[ch[i][z]] += 1ll*v*f[i]%mod) %= mod;
			else if (id[i] < n) (f[tr[id[i]+1].rt+1] += 1ll*v*f[i]%mod) %= mod;  
		}
		(ans += f[i]) %= 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;
}