#include <bits/stdc++.h>
using namespace std;
const int maxn = 601;
const int INF = 1e9 + 10;
queue<int> q;
int v, e, n, k, a, b, t;
int st[maxn];
bool vis[maxn];
int dist[maxn][maxn];
vector<pair<int, int> > path[maxn];
vector<int> match[maxn];
int ptr[maxn];
bool dfs(int p) {
  for (int i = 0; i < match[p].size(); i++)
    if (!vis[match[p][i]]) {
      vis[match[p][i]] = true;
      if (ptr[match[p][i]] == 0 || dfs(ptr[match[p][i]])) {
        ptr[match[p][i]] = p;
        return true;
      }
    }
  return false;
}
bool judge(int p) {
  for (int i = 1; i <= n; i++) {
    match[i].clear();
    for (int j = 1; j <= v; j++)
      if (dist[i][j] <= p) match[i].push_back(j);
  }
  for (int i = 1; i <= v; i++) ptr[i] = 0;
  int cnt = 0;
  for (int i = 1; i <= n; i++) {
    memset(vis, false, sizeof(vis));
    if (dfs(i)) cnt++;
  }
  return cnt >= k;
}
int main() {
  scanf("%d%d%d%d", &v, &e, &n, &k);
  for (int i = 1; i <= n; i++) scanf("%d", &st[i]);
  for (int i = 1; i <= e; i++) {
    scanf("%d%d%d", &a, &b, &t);
    path[a].push_back(make_pair(b, t));
    path[b].push_back(make_pair(a, t));
  }
  for (int i = 1; i <= n; i++) {
    q.push(st[i]);
    for (int j = 1; j <= v; j++) dist[i][j] = INF;
    dist[i][st[i]] = 0;
    vis[st[i]] = true;
    while (!q.empty()) {
      int cur = q.front();
      q.pop();
      vis[cur] = false;
      for (int j = 0; j < path[cur].size(); j++)
        if (dist[i][path[cur][j].first] > dist[i][cur] + path[cur][j].second) {
          dist[i][path[cur][j].first] = dist[i][cur] + path[cur][j].second;
          if (!vis[path[cur][j].first]) {
            q.push(path[cur][j].first);
            vis[path[cur][j].first] = true;
          }
        }
    }
  }
  int l = -1, r = 1731312;
  if (!judge(r)) {
    printf("-1\n");
    return 0;
  }
  while (l + 1 < r) {
    int mid = (l + r) >> 1;
    if (judge(mid))
      r = mid;
    else
      l = mid;
  }
  printf("%d\n", r);
  return 0;
}
