include[HTML_REMOVED]

define pii pair[HTML_REMOVED]

using namespace std;

const int M = 1010;
int n, m, s, w, ans = 1e9 + 7;

struct node{
int to, v;
};
vector[HTML_REMOVED] e[M];

void add(int a, int b, int c) {
e[a].push_back({b, c});
}

int dist[M], vis[M], flag;
void dij(int star) {
priority_queue[HTML_REMOVED], greater[HTML_REMOVED] > q;

memset(vis, 0, sizeof vis);
memset(dist, 0x3f3f3f3f, sizeof dist);
dist[star] = 0;
q.push(make_pair(0, star));

while (!q.empty()) {
    int now = q.top().second;  q.pop();

    if (vis[now]) continue;

    for (int i = 0;i < e[now].size();i ++) {
        int to = e[now][i].to, v = e[now][i].v;
        if (to == s && !flag) flag = true;
        if (dist[to] > dist[now] + v) {
            dist[to] = dist[now] + v;
            q.push(make_pair(dist[to], to));
        }

    }

}

}

int main(){

while (scanf("%d%d%d", &n, &m, &s) != -1) {
    ans = 0x3f3f3f3f; flag = false;

    for (int i = 1;i <= m;i ++) {
        int p, q, t;
        cin >> p >> q >> t;

        add(p, q, t);

    }

    cin >> w;// cout << w << endl;

    for (int i = 1;i <= w;i ++) {
        int temp; cin >> temp;

        dij(temp);

        //cout << dist[s] << endl;
        ans = min(ans, dist[s]);

    }

    if(flag) cout << ans << endl;
    else cout << -1 << endl;
}







return 0;

}