#include<iostream>
#include<fstream>
using namespace std;
ifstream f("ubuntzei.in");
ofstream g("ubuntzei.out");
int viz[2000],a[2000][2000];
void citire(int a[2000][2000], int n, int m)
{
    int i,j,k,x,y,z;
    for(k=1;k<=m;k++)
    {
        f>>x; f>>y; f>>z;
        a[x][y]=z;
        a[y][x]=z;
    }
}
int drum_minim (int a[2000][2000], int n)
{
    int i,k,j;
    for(k=1;k<=n;k++)
        for(i=1;i<=n;i++)
            for(j=1;j<=n;j++)
                if(a[i][k] && a[k][j] && i != j && (a[i][j] > a[i][k] + a[k][j] || !a[i][j]))
                       a[i][j]=a[k][j]+a[i][k];
}
void permutare(int loc[10], int n)
{
    int aux = loc[1];
    for (int i=1;i<=n-1;i++)
    loc[i] = loc[i+1];
    loc[n] = aux;
}
int main()
{
    int n,m,loc[100],k,i,j,s=0,sum[10000], minn;
    f>>n; f>>m; f>>k;
    for(i=1;i<=k;i++)
        f>>loc[i];
    citire(a,n,m);
    drum_minim(a,n);

    g<<a[1][n];
}