#include<bits/stdc++.h>
#define ll long long
#define vi vector<int>
#define vll vector<ll>
#define eb emplace_back
#define pb push_back
#define all(v) v.begin(),v.end()
#define sz(v) ((int)v.size())
#define pii pair<int,int>
#define pll pair<ll,ll>
#define fi first
#define se second
#define umap unordered_map
using namespace std;
namespace qiqi {
	const int inf = 1e9;
	struct Trie {
		struct Node {
			vi ch; int k;
			Node() {
				ch.assign(26,-1);
				k = inf;
			}
		};
		vector<Node> a;
		Trie() {
			a.eb();
		}
		int ins(int x,int c,int k) {
			if (a[x].ch[c] == -1) {
				a[x].ch[c] = sz(a);
				a.eb();
			}
			x = a[x].ch[c];
			a[x].k = min(a[x].k,k);
			return x;
		}
	};
	void main() {
		int n,m;
		cin >> n >> m;
		vi c(m,inf); c[0] = 0;
		vector<string> s(n);
		for (int i = 0; i < n; i++) {
			cin >> s[i]; int k = sz(s[i]);
			c[k%m] = min(c[k%m],k/m+1);
		}
		for (int i = 1; i < m; i++) {
			if (c[i] != inf) {
				int g = __gcd(i,m);
				for (int j = 0; j < g; j++) {
					for (int k = 0,x = i,y = (x+i)%m; k < 2*m/g; k++,x = y,y = (y+i)%m) {
						c[y] = min(c[y],c[x]+c[i]+(y < x));
					}
				}
			}
		}
		Trie trie;
		for (int i = 0; i < n; i++) {
			int x = sz(s[i]),p = 0;
			for (int j = 0; j < x; j++) {
				int y = c[(m-(x-j-1)%m)%m]+(x-j-1+m-1)/m+1;
				if (y != inf) {
					p = trie.ins(p,s[i][j]-'a',y);
				}
			}
		}
		string t; cin >> t;
		n = sz(t);
		vi f(n+1,inf); f[0] = 0;
		for (int i = 0; i < n; i++) {
			if (f[i] != inf) {
				int p = 0;
				for (int j = i; j < n; j++) {
					p = trie.a[p].ch[t[j]-'a'];
					if (p == -1) {
						break;
					}
					f[j+1] = min(f[j+1],f[i]+trie.a[p].k);
				}
			}
		}
		if (f[n] == inf) {
			cout << "-1\n";
			return;
		}
		cout << f[n] << '\n';
	}
}
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);

	int T; cin >> T;
	while (T--) qiqi::main();
	return 0;
}