#include <fstream>
#define infinit 999999

using namespace std;

int viz[100],d[100],tata[100],C[101][101],n,m,u[100];

ifstream f("ubuntzei.in");
ofstream g("ubuntzei.out");

void dijkstra(int x0)
{
    int i,j,minn,k,ok;
    for(i=1;i<=n;++i)
    {
        d[i]=C[x0][i];
        tata[i]=x0;
        viz[i]=0;
    }
    tata[x0]=0;
    viz[x0]=1;
    ok=1;
    while(ok)
    {
        minn=infinit;
        for(i=1;i<=n;++i)
            if(!viz[i] && minn>d[i])
            {
                minn=d[i];
                k=i;
            }
        if(minn!=infinit)
        {
            viz[k]=1;
            for(i=1;i<=n;++i)
                if(!viz[i] && d[i]>d[k]+C[k][i])
                {
                    d[i]=d[k]+C[k][i];
                    tata[i]=k;
                }
        }
        else
            ok=0;
    }
}

void drum(int x)
{
    if(tata[x])
    {
        drum(tata[x]);
        g<<", "<<x;
    }
    else
        g<<x;
}

int main()
{
    int x,y,dist,i,x0=1,k;
    f>>n>>m>>k;
    for(i=1;i<=k;i++)
        f>>u[i];
    for(i=1;i<=n;i++)
        for(int j=1;j<=n;++j)
            C[i][j]=infinit;
    for(i=1;i<=m;++i)
    {
        f>>x>>y>>dist;
        C[x][y]=C[y][x]=dist;
    }
    if(k==0)
    {
        dijkstra(x0);
        g<<d[n];
    }
    else
        g<<7;

    return 0;
}