#include <cstdio>
#include <vector>
#include <queue>
#define N 2003
#define oo 1e9
#define file "ubuntzei"

using namespace std;

priority_queue<pair<int,int> > q;
vector<pair<int,int> > g[N];

int n,m,x,y,c,k;
int v[20]; //friends
int dist[N][N];

FILE *fw;

void Read()
{
    FILE *fr = fopen(file".in","r");

    fscanf(fr,"%d%d%d",&n,&m,&k);

    for(int i=1; i<=k; ++i)
        fscanf(fr,"%d",&v[i]);

    while(m--)
    {
        fscanf(fr,"%d%d%d",&x,&y,&c);
        g[x].push_back(make_pair(y,c));
        g[y].push_back(make_pair(x,c));
        dist[x][y] = dist[y][x] = c;
    }

    fclose(fr);
}

inline void Roy_Floyd()
{
    for(int i=1; i<=n; ++i)
        for(int j=1;j<=n; ++j)
            if(dist[i][j] == 0 && i!=j) dist[i][j] = oo;
    for(int k=1; k<=n; ++k)
        for(int i=1; i<=n; ++i)
            for(int j=1; j<=n; ++j)
                dist[i][j] = min(dist[i][j], dist[i][k] + dist[k][j]);
    /*for(int i=1; i<=n; ++i)
    {
        for(int j=1;j<=n; ++j)
            fprintf(fw,"%d ",dist[i][j]);
        fprintf(fw,"\n");
    }*/

}

int Solve()
{
    Roy_Floyd();

    if(k ==0) return dist[1][n];

    int sol = 0;
    return k;
}

int main()
{
    fw = fopen(file".out","w");
    Read();

    fprintf(fw,"%d",Solve());
    fclose(fw);
    return 0;
}