#include<cstdio>
#include<queue>
#define Nmx 2001
#define INF 3155745
#define Mx 23

using namespace std;

int n,m,k,c[Mx],cost[Nmx],viz[Nmx];
int mat[Mx][Mx],bst[32775][Mx];
queue<int> Q;
struct nod
{
    int inf,cost;
    nod *urm;
};
nod *G[Nmx];

void add(int x,int y,int c)
{
    nod *aux=new nod;
    aux->inf = y;
    aux->cost = c;
    aux->urm = G[x];
    G[x]=aux;
}

void citire()
{
    scanf("%d%d",&n,&m);
    scanf("%d",&k);
    c[0]=1;
    for(int i=1;i<=k;++i)
        scanf("%d",&c[i]);
    c[k+1]=n;
    int x,y,c;
    for(int i=1;i<=m;++i)
    {
        scanf("%d%d%d",&x,&y,&c);
        add(x,y,c);
        add(y,x,c);
    }
}

void belman(int x)
{
    for(int i=1;i<=n;++i)
    {
        cost[i]=INF;
        viz[i]=0;
    }
    Q.push(x);
    cost[x]=0;
    viz[x]=1;
    while(!Q.empty())
    {
        int y = Q.front();
        Q.pop();
        viz[y]=0;
        for(nod *p=G[y];p;p=p->urm)
            if(cost[p->inf]>cost[y]+p->cost)
            {
                cost[p->inf]=cost[y]+p->cost;
                if(!viz[p->inf])
                {
                    Q.push(p->inf);
                    viz[p->inf]=1;
                }
            }
    }
}

int main()
{
    freopen("ubuntzei.in","r",stdin);
    freopen("ubuntzei.out","w",stdout);
    citire();
    for(int i=0;i<=k;++i)
    {
        belman(c[i]);
        for(int j=1; j<=k+1; ++j)
            mat[i][j]=cost[c[j]];

    }
    int oldstare;
    if(!k)
        printf("%d\n",mat[0][1]);
    else
    {
        memset(bst,INF,sizeof(bst));
        for(int stare=0;stare<(1<<k);++stare)
            for(int i=1;i<=k;++i)
             if(stare&(1<<(i-1)))
            {
                oldstare=stare^(1<<(i-1));
                if (!oldstare)
                    bst[stare][i]=mat[0][i];
                else
                    for (int j=1; j<=k; ++j)
                        if (oldstare&(1<<(j-1)))
                            bst[stare][i]=min (bst[stare][i],bst[oldstare][j]+mat[i][j]);
            }
        int sol=INF;
        for(int j=1;j<=k;++j)
            sol=min(sol,bst[(1<<k)-1][j]+mat[j][k+1]);
        if(sol==INF)
            printf("-1\n");
        else printf("%d\n",sol);
    }
    return 0;
}