#include <bits/stdc++.h>
using namespace std;
struct edge {
  int to;
  int cap;
  int rev;
  double cost;
};
int V;
vector<edge> G[105];
double h[105];
double dist[105];
int prevv[105], preve[105];
void init_edge() {
  for (int i = 0; i < 105; i++) G[i].clear();
}
void add_edge(int from, int to, int cap, double cost) {
  G[from].push_back((edge){to, cap, (int)G[to].size(), cost});
  G[to].push_back((edge){from, 0, (int)G[from].size() - 1, -cost});
}
double min_cost_flow(int s, int t, int f) {
  double eps = 1e-8;
  double res = 0;
  fill(h, h + V, 0.0);
  while (f > 0) {
    priority_queue<pair<double, int>, vector<pair<double, int> >,
                   greater<pair<double, int> > >
        que;
    fill(dist, dist + V, (double)1000000001);
    dist[s] = 0;
    que.push(pair<double, int>(0, s));
    while (!que.empty()) {
      pair<double, int> p = que.top();
      que.pop();
      int v = p.second;
      if (dist[v] + eps < p.first) continue;
      for (int i = 0; i < (int)G[v].size(); i++) {
        edge &e = G[v][i];
        if (e.cap > 0 && dist[e.to] > eps + dist[v] + e.cost + h[v] - h[e.to]) {
          dist[e.to] = dist[v] + e.cost + h[v] - h[e.to];
          prevv[e.to] = v;
          preve[e.to] = i;
          que.push(pair<double, int>(dist[e.to], e.to));
        }
      }
    }
    if (dist[t] > 1000000001 - eps) {
      return -1;
    }
    for (int v = 0; v < V; v++) h[v] += dist[v];
    int d = f;
    for (int v = t; v != s; v = prevv[v]) {
      d = min(d, G[prevv[v]][preve[v]].cap);
    }
    if (d == 0) break;
    f -= d;
    res += d * h[t];
    for (int v = t; v != s; v = prevv[v]) {
      edge &e = G[prevv[v]][preve[v]];
      e.cap -= d;
      G[v][e.rev].cap += d;
    }
  }
  return res;
}
vector<double> gauss_jordan(const vector<vector<double> > &A,
                            const vector<double> &b) {
  int n = A.size();
  vector<vector<double> > B(n, vector<double>(n + 1));
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++) B[i][j] = A[i][j];
  for (int i = 0; i < n; i++) B[i][n] = b[i];
  for (int i = 0; i < n; i++) {
    int pivot = i;
    for (int j = i; j < n; j++)
      if (abs(B[j][i]) > abs(B[pivot][i])) pivot = j;
    swap(B[i], B[pivot]);
    if (abs(B[i][i]) < 0.0000001) return vector<double>();
    for (int j = i + 1; j <= n; j++) B[i][j] /= B[i][i];
    for (int j = 0; j < n; j++) {
      if (i != j)
        for (int k = i + 1; k <= n; k++) B[j][k] -= B[j][i] * B[i][k];
    }
  }
  vector<double> x(n);
  for (int i = 0; i < n; i++) x[i] = B[i][n];
  return x;
}
int N, si, ti, F;
int M;
int main() {
  int T;
  cin >> T;
  while (T--) {
    init_edge();
    cin >> N >> si >> ti >> F;
    vector<vector<double> > A(N, vector<double>(N));
    vector<double> B(N);
    for (int i = 0; i < N; i++) {
      for (int j = 0; j < N; j++) scanf("%lf", &A[i][j]);
      scanf("%lf", &B[i]);
    }
    vector<double> C = gauss_jordan(A, B);
    for (int i = 0; i < N; i++) {
      cin >> M;
      vector<int> d(M);
      vector<int> f(M);
      for (int j = 0; j < M; j++) scanf("%d", &d[j]);
      for (int j = 0; j < M; j++) scanf("%d", &f[j]);
      for (int j = 0; j < M; j++) {
        add_edge(i, d[j], f[j], abs(C[i] - C[d[j]]));
      }
    }
    V = N;
    double ans = min_cost_flow(si, ti, F);
    if (ans <= -1.0) {
      cout << "impossible" << endl;
    } else {
      printf("%.10f\n", ans);
    }
  }
  return 0;
}
