c

#include <iostream>
#include <vector>
#include <queue>
#include <string.h>
#include <deque>
using namespace std;

vector<pair<int, int>> g[10000];
int path[10000][501];
char tr[10000];

struct vert {
    int value;
    int ver;
    int cruel;
    vert(int a, int b, int c) :value(a), ver(b), cruel(c) {}
    const bool operator < (const vert& x) const {
        return value < x.value;
    }
};


int main() {
    // yur code goes here
    int k, n, m, s, f;
    cin >> k >> n >> m >> s >> f;
    s--;
    f--;
    for (int i = 0; i < m; i++) {
        int u, v, l;

        cin >> u >> v >> l;
        u--;
        v--;
        if (l <= k) {
            g[u].push_back(make_pair(v, l));
            g[v].push_back(make_pair(u, l));
        }
    }
    int q;
    cin >> q;
    for (int i = 0; i < q; i++) {
        int a;
        cin >> a;
        tr[a - 1] = 1;
    }
    memset(path, 0x7F, sizeof(path));
    path[s][k] = 0;
    deque<vert> deq;
    deq.push_front(vert(0, s, k));
    while (!deq.empty()) {
        vert cur = deq.front();
        deq.pop_front();
        for (auto z : g[cur.ver]) {
            if (z.second <= cur.cruel)
                if (path[z.first][cur.cruel - z.second] > cur.value) {
                    path[z.first][cur.cruel - z.second] = cur.value;

                    deq.push_front(vert(cur.value, z.first, cur.cruel - z.second));
                }
            if (tr[cur.ver])
                if (path[z.first][k - z.second] > cur.value + 1) {
                    path[z.first][k - z.second] = cur.value + 1;

                    deq.push_back(vert(cur.value + 1, z.first, k - z.second));
                }
        }
    }
    int res = 1e9;
    for (int i = 0; i <= k; i++)
        res = min(res, path[f][i]);
    if (res == 1e9)
        res = -1;
    cout << res;
    return 0;
}