#include <iostream>
#include <fstream>
using namespace std;

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

const int NMAX = 2000 + 5;
const int INF=100000000;
int n , m , mat[NMAX][NMAX], c, k[NMAX], dp[NMAX][NMAX], kk;


void dinam(int x)
{

}

int main()
{
    f >> n >> m;
    int i, x, y;
    f >> kk;
    for (i = 1; i <= kk; ++i)
        f >> k[i] ;

    for (i = 1 ; i <= m ; ++i)
    {
        f >> x >> y >> c;
        mat[x][y] = c;
        mat[y][x] = c;
    }

int j ,ki;
    for(int ki=1;ki<=n;ki++)
        for(i=1;i<=n;i++)
            for(j=1;j<=n;j++)
                if((mat[i][j]>mat[i][ki]+mat[ki][j]||!mat[i][j])&&mat[i][ki]&&mat[ki][j]&&i!=j)
                    mat[i][j]=mat[i][ki]+mat[ki][j];

    if (!kk) fout<<mat[1][n];

   /* for (i = 1; i <= n ; ++i)
        {for ( int j = 1 ; j <= n; ++j)
    {
        cout << mat[i][j] << " ";


    }
    cout << endl;
        }*/
    return 0;
}