#include <iostream>
#include <string.h>
#include <queue>

using namespace std;

struct node{
    int d;
    int r;

    bool operator>(const node& n)const{
        return d>n.d;
    }
};

int n,h,m,a,b,t,c;
bool is_hotel[10010];
vector<pair<int,int> > rds[10010];
vector<int> r_bfs[10010];
priority_queue<node,vector<node>,greater<node> > q;
queue<node> qu;
node top;
bool vis[10010];

int main()
{
    while(1){
        cin>>n;
        if(n==0)break;
        cin>>h;
        memset(is_hotel,0,sizeof(is_hotel)/sizeof(bool));
        for(int i=0;i<h;i++){cin>>c; is_hotel[c-1]=true;}

        cin>>m;
        while(m--){
            cin>>a>>b>>t;
            a--; b--;
            rds[a].push_back(make_pair(t,b));
            rds[b].push_back(make_pair(t,a));
        }

        // DIJSKTRA
        for(int i=0;i<n;i++){
            if(!(is_hotel[i] || i==0))continue;
            memset(vis,0,sizeof(vis)/sizeof(bool));
            q=priority_queue<node,vector<node>,greater<node> >();
            q.push({0,i});

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

                if(vis[top.r] || top.d>600)continue;
                vis[top.r]=true;

                if((top.r!=i) && (top.r==n-1 || is_hotel[top.r]))r_bfs[i].push_back(top.r);

                for(int j=0;j<rds[top.r].size();j++){
                    q.push({top.d+rds[top.r][j].first,rds[top.r][j].second});
                }
            }
        }

        for(int i=0;i<n;i++)
            rds[i].clear();

        // BFS
        memset(vis,0,sizeof(vis)/sizeof(bool));
        qu = queue<node>();
        qu.push({0,0});
        bool f=false;

        while(!qu.empty()){
            top=qu.front();
            qu.pop();

            if(vis[top.r])continue;
            vis[top.r]=true;

            if(top.r==n-1){f=1; break;}

            for(int j=0;j<r_bfs[top.r].size();j++){
                qu.push({top.d+((r_bfs[top.r][j]==n-1)?0:1),r_bfs[top.r][j]});
            }
        }

        for(int i=0;i<n;i++)
            r_bfs[i].clear();

        if(f)
            cout<<top.d<<endl;
        else
            cout<<"-1"<<endl;
    }
}