#include <set>
#include <vector>
#include <cstring>
#include <cstdio>
#include <algorithm>

using namespace std;

#define MAX_N 100000

#define trav(it, cont) for(typeof(cont.begin()) it = cont.begin(); it != cont.end(); it++)

typedef pair<int, int> pii;
vector<vector<pii> > adj;
int visited[MAX_N];
int best[MAX_N];
int secondBest[MAX_N];

int travel_plan(int N, int M,int R[][2],int L[], int K, int P[]){
  //in case called again - not sure how the IOI judge would do
  adj.clear();
  adj.resize(N);
  memset(visited, 0, sizeof(visited));
  memset(best, -1, sizeof(best));
  memset(secondBest, -1, sizeof(secondBest));
  for(int i = 0; i<M; i++){
    int t = R[i][0];
    int f = R[i][1];
    adj[t].push_back(pii(f, L[i]));
    adj[f].push_back(pii(t, L[i]));
  }
  set<pii> pq;
  for(int i = 0; i<K; i++){
    pq.insert(pii(0, P[i]));
  }

  while(!pq.empty()){
    pii v = *(pq.begin());
    pq.erase(pq.begin());
    trav(u, adj[v.second]) {
      pii uu = *u;
      visited[uu.first]++;
      int distance = uu.second + v.first;
      if(visited[uu.first] == 1){
    best[uu.first] = distance;
      } else if(visited[uu.first] == 2){
    int lowest = min(best[uu.first], distance);
    int highest = max(best[uu.first], distance);
    best[uu.first] = lowest;
    secondBest[uu.first] = highest;
    pq.insert(pii(highest, uu.first));
      } else {
    if(distance > secondBest[uu.first]) continue;
    pq.erase(pii(secondBest[uu.first], uu.first));
    int bestX, secondBestX;
    if(distance < best[uu.first]){
      bestX = distance;
      secondBestX = best[uu.first];
    } else {
      bestX = best[uu.first];
      secondBestX = distance;
    }
    best[uu.first] = bestX;
    secondBest[uu.first] = secondBestX;
    pq.insert(pii(secondBestX, uu.first));
      }
    }
  }
  return secondBest[0];
}

void case1(){
  int n = 5;
  int m = 4;
  int k = 3;
  int r[][2] = {
    {0, 1},
    {0, 2},
    {3, 2},
    {2, 4}
  };
  int l[] = {2, 3, 1, 4};
  int p[] = {1, 3, 4};
  printf("%d\n", travel_plan(n, m, r, l, k, p));
}

void case2(){
  int n = 5;
  int m = 7;
  int k = 2;
  int r[][2] = {
    {0, 2},
    {0, 3},
    {3, 2},
    {2, 1},
    {0, 1},
    {0, 4},
    {3, 4},
  };
  int l[] = {4, 3, 2, 10, 100, 7, 9};
  int p[] = {1, 3};
  printf("%d\n", travel_plan(n, m, r, l, k, p));
}

int main(){
  case1();
  case2();
}