#include<stdio.h>
#include<string.h>
#include<stdbool.h>

#define N 1010
#define M 21010
#define INF 0x3f3f3f3f

int n, m, s;
int p, q, t, w;
int dist[N];
int que[N];
bool inQue[N];
int head, tail;
int h[N], cnt;
int start;

struct edge{
    int to;
    int next;
    int weight;
}E[M];

void add(int v, int w, int weight){
    E[++cnt].next = h[v];
    E[cnt].to = w;
    E[cnt].weight = weight;
    h[v] = cnt;
}

int spfa(int x){
    memset(dist, 0x3f, sizeof dist);
    memset(inQue, false, sizeof inQue);
    head = 0, tail = 0;
    dist[x] = 0;
    que[++tail] = x, inQue[x] = true;

    while(head != tail){
        int t = que[++head];
        head %= N;
        inQue[t] = false;

        for(int i = h[t]; i != -1; i = E[i].next){
            int u = E[i].to;
            if(dist[u] > dist[t] + E[i].weight){
                dist[u] = dist[t] + E[i].weight;
                if(!inQue[u]){
                    que[++tail] = u;
                    tail %= N;
                    inQue[u] = true;
                }
            }
        }
    }

    if(dist[s] == INF)  return -1;
    else return dist[s];
}

int main(){

    while(scanf("%d %d %d", &n, &m, &s) != EOF){
        memset(h, -1, sizeof h);
        cnt = 0;
        for(int i = 1; i <= m; i++){
            scanf("%d %d %d", &p, &q, &t);
            add(p, q, t);
        }

        scanf("%d", &w);
        for(int i = 1; i <= w; i++){
            scanf("%d", &start);
            add(0, start, 0);
        }

        printf("%d\n", spfa(0));
    }
    return 0;
}