#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
int n , k;
string s[1000005];
set<int> st;
vector<pair<int,int> > E[5005];
int dis[5005];
void dij()
{
    priority_queue<pair<int,int> , vector<pair<int,int> > , greater<pair<int,int> > > pq;
    for(int i = 0;i < k;i++) dis[i] = 1e9;
    dis[0] = 0;
    pq.push(pair<int,int>{0 , 0});
    while(pq.size()) {
        int u = pq.top().second ; pq.pop();
        for(auto &[v , w] : E[u]) {
            if(dis[u] + w < dis[v]) {
                dis[v]  =dis[u] + w;
                pq.push(pair<int,int>{dis[v] , v});
            }
        }
    }
    return;
}
struct trie {
    int mn;
    int ch[26];
    cls() {
        memset(ch,0,sizeof(ch));
        mn = 1e9;
    }
}T[1000005];
int cnt ;
inline int get(int x)
{
    return x/k + dis[x % k];
}
void ins(const string &s)
{
    int u = 0;
    for(int i = 0;i < s.size();i++) {
        int t = s[i] - 'a';
        if(!T[u].ch[t]) {
            T[u].ch[t] = ++cnt ; T[cnt].cls();
        }
        u = T[u].ch[t];
        T[u].mn = min(T[u].mn , get(s.size() - i - 1) + 1);
    }
    return;
}
ll dp[5005];
void solve()
{
    cin >> n >> k; st.clear();cnt = 0; T[0].cls();
    for(int i = 0;i < k;i++) E[i].clear();
    for(int i = 1;i <= n;i++) {
        cin >> s[i]; st.insert(s[i].size());
    }
    for(auto L : st) {
        for(int i = 0;i < k;i++) { /// (u + L) mod k = i
            int u = (i - L%k + k) % k;
            E[i].push_back(pair<int,int>{u , (u + L) / k + 1}) ;
        }
    }
    dij() ;
   // for(int i = 0;i < k;i++) printf("dist %d %d\n",i,dis[i]);
    for(int i = 1;i <= n;i++) {
        ins(s[i]);
    }
    string t;cin >> t;
    dp[0] = 0;
    for(int i = 1;i <= t.size();i++) dp[i] = 1e18;
    for(int i = 0;i < t.size();i++) {
        int u = 0;
        for(int j = i + 1;j <= t.size();j++) {
            u = T[u].ch[t[j - 1] - 'a'] ;
            if(!u) break;
            dp[j] = min(dp[j] , dp[i] + T[u].mn);
        }
    }
    if(dp[t.size()] > 1e17) cout << -1 << '\n';
    else cout << dp[t.size()] << '\n';
}
int main()
{
   // freopen("in.txt","r",stdin);
    ios::sync_with_stdio(false) ; cin.tie(0) ; cout.tie(0);
    int t;cin >> t;
    while(t--) solve();
    return 0;
}

answer.code:29:5: error: ISO C++ forbids declaration of ‘cls’ with no type [-fpermissive]
   29 |     cls() {
      |     ^~~
answer.code: In member function ‘int trie::cls()’:
answer.code:32:5: warning: no return statement in function returning non-void [-Wreturn-type]
   32 |     }
      |     ^