#include <bits/stdc++.h>
using namespace std;
const int N = 201;
const int maxn = 601;
int n, m, nn;
vector<int> cites[maxn];
int mp[N][maxn], link[maxn], k, used[maxn], cnt, Mp[maxn][maxn], city[maxn];
void floyd() {
  for (int h = 1; h <= n; h++)
    for (int j = 1; j <= n; j++)
      for (int i = 1; i <= n; i++)
        if (i != j && i != h && j != h)
          Mp[j][i] = min(Mp[j][i], Mp[j][h] + Mp[h][i]);
}
bool dfs(int u, int Max) {
  for (int i = 1; i <= n; i++) {
    if (mp[u][i] <= Max && !used[i]) {
      used[i] = 1;
      if (link[i] == -1 || dfs(link[i], Max)) {
        link[i] = u;
        return true;
      }
    }
  }
  return false;
}
int Hungary(int Max) {
  int ans = 0;
  memset(link, -1, sizeof(link));
  for (int i = 1; i <= nn; i++) {
    memset(used, 0, sizeof(used));
    if (dfs(i, Max)) ans++;
  }
  if (ans < k) return 0;
  return 1;
}
int main() {
  scanf("%d %d %d %d", &n, &m, &nn, &k);
  for (int i = 0; i <= n; i++) cites[i].clear();
  cnt = 0;
  int u, v, w;
  for (int i = 1; i <= nn; i++) {
    scanf("%d", &u);
    if (!cites[u].size()) city[cnt++] = u;
    cites[u].push_back(i);
  }
  memset(Mp, 0x3f, sizeof(Mp));
  memset(mp, 0x3f, sizeof(mp));
  for (int i = 0; i < m; i++) {
    scanf("%d %d %d", &u, &v, &w);
    Mp[u][v] = min(Mp[u][v], w);
    Mp[v][u] = Mp[u][v];
  }
  if (k < cnt) {
    puts("0");
    return 0;
  }
  floyd();
  for (int i = 0; i < cnt; i++) {
    u = city[i];
    for (int j = 0; j < cites[u].size(); j++) {
      int v = cites[u][j];
      for (int h = 1; h <= n; h++) {
        if (h == u)
          mp[v][u] = 0;
        else if (Mp[u][h] != 0x3f3f3f3f)
          mp[v][h] = Mp[u][h];
      }
    }
  }
  int l = 0, r = 1731311, mid;
  while (l <= r) {
    mid = (l + r) / 2;
    int ans = Hungary(mid);
    if (ans)
      r = mid - 1;
    else
      l = mid + 1;
  }
  if (l > 1731311)
    puts("-1");
  else
    printf("%d\n", l);
  return 0;
}
