#include <cstdio>
#include <queue>
#define Nmax 2005
#define INF 2000000000

using namespace std;

int N,K,dp[Nmax][20];
bool loc[Nmax];

struct Edge
{
    int nod,cost;
};
struct el
{
    int nod,nr,dp;
    bool operator <(const el A) const
    {
        return dp>A.dp;
    }
};
priority_queue <el> Q;
vector <Edge> L[Nmax];

inline void Dinamic()
{
    el w,w1;
    vector <Edge>::iterator it;
    w.nod=1; w.nr=0; w.dp=0;
    Q.push(w);
    while(!Q.empty())
    {
        w=Q.top(); Q.pop();
        if(w.nod==N && w.nr==K)
            return;
        for(it=L[w.nod].begin();it!=L[w.nod].end();++it)
        {
            w1.nod=it->nod;
            w1.nr=w.nr;
            if(loc[w1.nod]) ++w1.nr;
            w1.dp=w.dp+it->cost;
            if(w1.dp<dp[w1.nod][w1.nr])
            {
                dp[w1.nod][w1.nr]=w1.dp;
                Q.push(w1);
            }
        }
    }
}

int main()
{
    int M,i,j,x,y,z;
    Edge w;
    freopen ("ubuntzei.in","r",stdin);
    freopen ("ubuntzei.out","w",stdout);
    scanf("%d%d%d", &N,&M,&K);
    for(i=1;i<=K;++i)
    {
        scanf("%d", &x);
        loc[x]=true;
    }
    while(M--)
    {
        scanf("%d%d%d", &x,&y,&z);
        w.nod=y; w.cost=z;
        L[x].push_back(w);
        w.nod=x;
        L[y].push_back(w);
    }
    for(i=1;i<=N;++i)
        for(j=0;j<=K;++j)
            dp[i][j]=INF;
    dp[1][0]=0;
    Dinamic();
    printf("%d\n", dp[N][K]);
    return 0;
}