#include<bits/stdc++.h>
#define pii pair<int, int>
#define fi first
#define se second
using namespace std;
typedef long long ll;
const int N = 1e6 + 6;
const int K = 5005;

string s[N], t;
map<int, int> cost;
int ch[N][26], dis[K], mn[N];
int T, n, k, m, siz;
ll f[K];

void insert(string s) {
    int p = 1;
    for(auto c : s) {
        int &to = ch[p][c - 'a'];
        if(!to) to = ++ siz;
        p = to;
    }
}
inline int add(int a, int b) { return a + b >= k ? a + b - k : a + b; }

void solve() {
    for(int i = 1; i <= siz; ++ i)
        memset(ch[i], 0, sizeof(ch[i]));
    siz = 1, cost.clear();

    cin >> n >> k;
    for(int i = 1; i <= n; ++ i) {
        cin >> s[i], insert(s[i]);
        int len = s[i].size(), l = len % k;
        if(l == 0) continue;
        if(cost.find(l) == cost.end())
            cost[l] = len / k + 1;
        else cost[l] = min(cost[l], len / k + 1);
    }
    cin >> t, m = t.size();

    memset(dis, 127, (k + 5) << 2), dis[0] = 0;
    for(auto edge : cost) 
        for(int j = 0, lim = __gcd(k, edge.fi); j < lim; ++ j)
            for(int cur = j, cnt = 0, nex; cnt < 2; cnt += cur == j)
                nex = add(cur, edge.fi), dis[nex] = min(dis[nex], dis[cur] + edge.se + (cur > nex)), cur = nex;

    // for(int i = 0; i < k; ++ i)
        // cout << dis[i] << " "; cout << endl;

    memset(mn, 127, (siz + 5) << 2);
    for(int i = 1; i <= n; ++ i) {
        int p = 1, len = s[i].size();
        for(int j = 0; j < len; ++ j) {
            p = ch[p][s[i][j] - 'a'];
            int rst = len - j - 1;
            mn[p] = min(mn[p], rst / k + dis[rst % k]);
        }
    }
    // for(int i = 1; i <= siz; ++ i)
        // cout << mn[i] << " " ; cout << endl;

    memset(f, 127, (m + 5) << 3), f[0] = 0;
    for(int i = 0; i <= m; ++ i)
        for(int j = i + 1, p = 1; j <= m; ++ j) {
            p = ch[p][t[j - 1] - 'a'];
            if(!p) break;
            if(!(mn[p] >> 29))
                f[j] = min(f[j], f[i] + mn[p] + 1);
        }
    if(f[m] >> 60) cout << "-1\n";
    else cout << f[m] << '\n';
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);

    cin >> T;
    while(T --) solve();    
    return 0;
}