#include <bits/stdc++.h>

using i64 = long long;

constexpr i64 inf = 1E18;

constexpr int N = 1E6 + 10;

int trie[N][26];
i64 val[N];
int tot;

int newNode() {
    tot++;
    std::fill(trie[tot], trie[tot] + 26, 0);
    val[tot] = inf;
    return tot;
}

void solve() {
    int N, K;
    std::cin >> N >> K;
    
    std::vector<std::string> S(N);
    for (int i = 0; i < N; i++) {
        std::cin >> S[i];
    }
    
    std::string T;
    std::cin >> T;
    
    int L = T.size();
    
    std::vector<i64> min(K, inf);
    min[0] = 0;
    for (int i = 0; i < N; i++) {
        int l = S[i].size();
        min[l % K] = std::min(min[l % K], 1LL * l + K);
    }
    
    std::vector<i64> f(K, inf);
    f[0] = 0;
    for (int i = 0; i < K; i++) {
        int g = std::gcd(K, i);
        for (int j = 0; j < g; j++) {
            for (int k = 0; k < K / g * 2; k++) {
                int a = (j + k * i) % K;
                int b = (j + (k + 1) * i) % K;
                f[b] = std::min(f[b], f[a] + min[i]);
            }
        }
    }
    
    tot = 0;
    newNode();
    
    for (int i = 0; i < N; i++) {
        int p = 1;
        for (int j = 0; j < S[i].size(); j++) {
            int x = S[i][j] - 'a';
            if (!trie[p][x]) {
                trie[p][x] = newNode();
            }
            p = trie[p][x];
            val[p] = std::min(val[p], int(S[i].size()) + K + f[(K - (S[i].size() - j - 1) % K) % K]);
        }
    }
    
    std::vector<i64> dp(L + 1, inf);
    dp[0] = 0;
    for (int i = 0; i < L; i++) {
        int p = 1;
        for (int j = i; j < L; j++) {
            int x = T[j] - 'a';
            p = trie[p][x];
            if (!p) {
                continue;
            }
            dp[j + 1] = std::min(dp[j + 1], dp[i] + val[p]);
        }
    }
    i64 ans = dp[L];
    if (ans == inf) {
        ans = -1;
    } else {
        ans = (ans - L) / K;
    }
    std::cout << ans << "\n";
}

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    
    int t;
    std::cin >> t;
    
    while (t--) {
        solve();
    }
    
    return 0;
}