#include <fstream>
using namespace std;

ifstream F("team.in");
ofstream G("team.out");

const int N = 510;
const int M = 55;

int cst[N][N],n,m,mm;
int d[M][M][M],dst[N];

int main()
{
    F>>m>>n>>mm;
    for (int i=1;i<=n;++i)
        for (int j=1;j<=n;++j)
            if ( i != j )
                cst[i][j] = 1<<29;
    for (int i=1,x,y,c;i<=mm;++i)
    {
        F>>x>>y>>c;
        cst[x][y] = min(cst[x][y],c);
        cst[y][x] = min(cst[y][x],c);
    }
    for (int k=1;k<=n;++k)
        for (int i=1;i<=n;++i)
            for (int j=1;j<=n;++j)
                cst[i][j] = min(cst[i][j],cst[i][k]+cst[k][j]);
    for (int i=1;i<=m;++i)
        F>>dst[i];
    dst[0] = 1;
    for (int j=1;j<=m;++j)
        for (int i=j;i>=1;--i)
            for (int ds=0;ds<=m;++ds)
            {
                d[i][j][ds] = 1<<29;
                for (int l=i;l<=j;++l)
                {
                    int act = 0;
                    if ( i <= l-1 ) act += d[i][l-1][l];
                    if ( l+1 <= j ) act += d[l+1][j][l];
                    act += cst[dst[ds]][dst[l]];
                    d[i][j][ds] = min(d[i][j][ds],act);
                }
            }
    G<<d[1][m][0]<<'\n';
}