#include <bits/stdc++.h>
using namespace std;
struct MaxFlow {
  int T;
  struct node {
    int to, nxt, cap;
  } ed[811 * 811 << 1];
  int head[811], cur[811], cnt, ans;
  int h[811];
  void addedge(int u, int v, int cap) {
    ed[cnt].to = v, ed[cnt].cap = cap, ed[cnt].nxt = head[u], head[u] = cnt++;
    ed[cnt].to = u, ed[cnt].cap = 0, ed[cnt].nxt = head[v], head[v] = cnt++;
  }
  bool bfs() {
    memset(h, -1, sizeof(h));
    queue<int> q;
    h[1] = 0, q.push(1);
    while (!q.empty()) {
      int now = q.front();
      q.pop();
      for (int i = head[now]; ~i; i = ed[i].nxt) {
        if (ed[i].cap && h[ed[i].to] == -1) {
          h[ed[i].to] = h[now] + 1;
          q.push(ed[i].to);
        }
      }
    }
    return h[T] != -1;
  }
  int dfs(int x, int f) {
    if (x == T || f == 0) return f;
    int w, used = 0;
    for (int i = cur[x]; ~i; i = ed[i].nxt) {
      if (h[ed[i].to] == h[x] + 1) {
        w = f - used;
        w = dfs(ed[i].to, min(w, ed[i].cap));
        ed[i].cap -= w;
        ed[i ^ 1].cap += w;
        if (ed[i].cap) cur[x] = i;
        used += w;
        if (used == f) return f;
      }
    }
    if (!used) h[x] = -1;
    return used;
  }
  void dinic() {
    while (bfs()) {
      for (int i = 1; i <= T; i++) {
        cur[i] = head[i];
      }
      ans += dfs(1, 100000005);
    }
  }
  void init(int t) {
    memset(head, -1, sizeof(head));
    ans = cnt = 0;
    T = t;
  }
} flow;
int dis[811][811], st[811];
int main() {
  int v, e, n, k;
  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 <= v; i++)
    for (int j = i + 1; j <= v; j++) dis[i][j] = dis[j][i] = 100000005;
  for (int i = 1; i <= e; i++) {
    int a, b, c;
    scanf("%d%d%d", &a, &b, &c);
    dis[a][b] = min(dis[a][b], c);
    dis[b][a] = dis[a][b];
  }
  for (int x = 1; x <= v; x++) {
    for (int i = 1; i <= v; i++) {
      for (int j = 1; j <= v; j++) {
        dis[i][j] = min(dis[i][x] + dis[x][j], dis[i][j]);
      }
    }
  }
  int l = 0, r = 1731311, ct = -1;
  while (l <= r) {
    int mid = l + r >> 1;
    flow.init(1 + n + v + 2);
    for (int i = 1; i <= n; i++) {
      flow.addedge(1, i + 1, 1);
      for (int j = 1; j <= v; j++) {
        if (dis[st[i]][j] <= mid) {
          flow.addedge(i + 1, 1 + j + n, 1);
        }
      }
    }
    for (int i = 1; i <= v; i++) flow.addedge(1 + i + n, 1 + v + n + 1, 1);
    flow.addedge(1 + v + n + 1, 1 + v + n + 2, k);
    flow.dinic();
    if (flow.ans == k) {
      ct = mid;
      r = mid - 1;
    } else
      l = mid + 1;
  }
  printf("%d\n", ct);
  return 0;
}
