#include <bits/stdc++.h>
#define int long long

using namespace std;

const int maxn = 2e3 + 1;
const int maxm = 2e3 + 1;
const int maxv = 3e2 + 1;
const int maxe = 9e4 + 1;
const int inf = 1e18;

int n, m, v, e;
int c[maxn];
int d[maxn];
double k[maxn];
int g[maxv][maxv];

double f[maxn][maxm][2];

void input() {
    cin >> n >> m >> v >> e;
    for (int i = 1; i <= n; i++) {
        cin >> c[i];
    }
    for (int i = 1; i <= n; i++) {
        cin >> d[i];
    }
    for (int i = 1; i <= n; i++) {
        cin >> k[i];
    }
    for (int i = 1, u, v, w; i <= e; i++) {
        cin >> u >> v >> w;
        if (g[u][v]) g[u][v] = g[v][u] = min(g[u][v], w);
        else g[u][v] = g[v][u] = w;
    }
}

void init() {
    for (int i = 0; i <= n; i++) {
        for (int j = 0; j <= m; j++) {
            f[i][j][0] = inf;
            f[i][j][1] = inf;
        }
    }
    f[1][0][0] = 0;
    f[1][1][1] = 0;
    for (int i = 2; i <= n; i++) {
        f[i][0][0] = f[i - 1][0][0] + g[c[i - 1]][c[i]];
    }
}

void floyd() {
    for (int k = 1; k <= v; k++) {
        for (int i = 1; i <= v; i++) {
            for (int j = 1; j <= v; j++) {
                if (i == j) continue;
                g[i][j] = min(g[i][j], g[i][k] + g[k][j]);
            }
        }
    }
}

void dp() {
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= m; j++) {
            f[i][j][0] = min(f[i][j][0], min(
                f[i - 1][j][0] + g[c[i - 1]][c[i]],
                f[i - 1][j][1] + (1 - k[i - 1]) * g[c[i - 1]][c[i]] + k[i - 1] * g[d[i - 1]][c[i]]
            ));
            f[i][j][1] = min(f[i][j][1], min(
                f[i - 1][j - 1][0] + (1 - k[i]) * g[c[i - 1]][c[i]] + k[i] * g[c[i - 1]][d[i]],
                f[i - 1][j - 1][1] + k[i - 1] * k[i] * g[d[i - 1]][d[i]] + k[i - 1] * (1 - k[i]) * g[d[i - 1]][c[i]] + (1 - k[i - 1]) * k[i] * g[c[i - 1]][d[i]] + (1 - k[i - 1]) * (1 - k[i]) * g[c[i - 1]][c[i]]
            ));
        }
    }
}

void output() {
    double ans = inf;
    for (int i = 0; i <= m; i++) {
        ans = min(ans, min(f[n][i][0], f[n][i][1]));
    }
    cout << fixed << setprecision(2) << ans << endl;
}

signed main() {
    input();
    floyd();
    init();
    dp();
    output();
    return 0;
}