import java.io.*;
import java.util.*;
class Main {
public static long fun1(int root, int parent, List<List<Pair>> adj, int[] parentArr, int[] levelArr, long[] shopArr, long[] costTillMeArr, HashSet<Integer> shopsSet, int currDepth, long costTillMe){
parentArr[root] = parent;
levelArr[root] = currDepth;
costTillMeArr[root] = costTillMe;
long minCost = (shopsSet.contains(root)) ? 0 : Long.MAX_VALUE;
for(Pair p: adj.get(root)) {
int x = p.node;
int w = p.weight;
if(x == parent) continue;
long res = fun1(x, root, adj, parentArr, levelArr, shopArr, costTillMeArr, shopsSet, currDepth + 1, costTillMe + w);
if(res == Long.MAX_VALUE) continue;
minCost = Math.min(minCost, res + w);
}
return shopArr[root] = minCost;
}
public static void fun2(int root, int parent, List<List<Pair>> adj, int[] inTimeArr, int[] outTimeArr, int[] timeArr){
inTimeArr[root] = timeArr[0];
timeArr[0]++;
for(Pair p: adj.get(root)) {
int x = p.node;
if(x == parent) continue;
fun2(x, root, adj, inTimeArr, outTimeArr, timeArr);
}
outTimeArr[root] = timeArr[0];
timeArr[0]++;
}
public static long[] fun(int n, int s, int q, int e, List<List<Pair>> adj, int[][] edges, int[] shopArr, int[][] queries) {
int[] parentArr = new int[n];
int[] levelArr = new int[n];
long[] nearestShopArr = new long[n];
long[] costTillMeArr = new long[n];
Arrays.fill(nearestShopArr, Long.MAX_VALUE);
HashSet<Integer> set = new HashSet<>();
for(int x: shopArr) {
set.add(x);
}
fun1(e, -1, adj, parentArr, levelArr, nearestShopArr, costTillMeArr, set, 0, 0);
int[] inTimeArr = new int[n];
int[] outTimeArr = new int[n];
fun2(e, -1, adj, inTimeArr, outTimeArr, new int[]{0});
// System.out.println("Printing parentArr: ");
// for(int i = 0; i < n; i++) {
// System.out.print(parentArr[i] +" ");
// }
// System.out.println("\n------------");
// System.out.println("Printing levelArr: ");
// for(int i = 0; i < n; i++) {
// System.out.print(levelArr[i] +" ");
// }
// System.out.println("\n------------");
// System.out.println("Printing nearest shop Arr: ");
// for(int i = 0; i < n; i++) {
// System.out.print(nearestShopArr[i] +" ");
// }
// System.out.println("\n------------");
// System.out.println("Printing cost till me Arr: ");
// for(int i = 0; i < n; i++) {
// System.out.print(costTillMeArr[i] +" ");
// }
// System.out.println("\n------------");
// System.out.println("Printing in Time Arr: ");
// for(int i = 0; i < n; i++) {
// System.out.print(inTimeArr[i] +" ");
// }
// System.out.println("\n------------");
// System.out.println("Printing out Time Arr: ");
// for(int i = 0; i < n; i++) {
// System.out.print(outTimeArr[i] +" ");
// }
// System.out.println("\n------------");
long[] ansArr = new long[q];
for(int i = 0; i < q; i++) {
int startVer = queries[i][1];
int node1 = edges[queries[i][0]][0], node2 = edges[queries[i][0]][1];
if(levelArr[node1] > levelArr[node2]){
int temp = node1;
node1 = node2;
node2 = temp;
}
if(!(inTimeArr[node2] <= inTimeArr[startVer] && outTimeArr[node2] >= outTimeArr[startVer])){
ansArr[i] = -1;
continue;
}
long minCost = Long.MAX_VALUE;
int ptr = startVer;
while(ptr != node1){
long costOfNearestShop = nearestShopArr[ptr];
if(costOfNearestShop != Long.MAX_VALUE){
minCost = Math.min(minCost, costOfNearestShop + costTillMeArr[startVer] - costTillMeArr[ptr]);
}
ptr = parentArr[ptr];
}
if(minCost != Long.MAX_VALUE) ansArr[i] = minCost;
else ansArr[i] = -2;
}
return ansArr;
}
public static void main(String[] args) throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
StringTokenizer st = new StringTokenizer(br.readLine());
int n = Integer.parseInt(st.nextToken());
int s = Integer.parseInt(st.nextToken());
int q = Integer.parseInt(st.nextToken());
int e = Integer.parseInt(st.nextToken()) - 1;
int[][] edges = new int[n - 1][2];
List<List<Pair>> adj = new ArrayList<>();
for(int i = 0; i < n; i++) {
adj.add(new ArrayList<>());
}
for(int i = 0; i < n - 1; i++) {
st = new StringTokenizer(br.readLine());
int x = Integer.parseInt(st.nextToken()) - 1;
int y = Integer.parseInt(st.nextToken()) - 1;
int w = Integer.parseInt(st.nextToken());
adj.get(x).add(new Pair(y, w));
adj.get(y).add(new Pair(x, w));
edges[i][0] = x;
edges[i][1] = y;
}
int[] shopArr = new int[s];
for(int i = 0; i < s; i++) {
st = new StringTokenizer(br.readLine());
shopArr[i] = Integer.parseInt(st.nextToken()) - 1;
}
int[][] queries = new int[q][2];
for(int i = 0; i < q; i++) {
st = new StringTokenizer(br.readLine());
int roadNum = Integer.parseInt(st.nextToken()) - 1;
int startVer = Integer.parseInt(st.nextToken()) - 1;
queries[i][0] = roadNum;
queries[i][1] = startVer;
}
long[] ansArr = fun(n, s, q, e, adj, edges, shopArr, queries);
for(int i = 0; i < q; i++) {
if(ansArr[i] == -1) bw.write("escaped" + "\n");
else if(ansArr[i] == -2) bw.write("oo" + "\n");
else bw.write(ansArr[i] + "\n");
}
br.close();
bw.flush();
bw.close();
}
}
class Pair {
int node;
int weight;
public Pair(int node, int weight) {
this.node = node;
this.weight = weight;
}
@Override
public boolean equals(Object obj) {
if (this == obj) return true;
if (obj == null || getClass() != obj.getClass()) return false;
Pair pair = (Pair) obj;
return node == pair.node && weight == pair.weight;
}
@Override
public int hashCode() {
return Objects.hash(node, weight);
}
@Override
public String toString() {
return "(" + node + ", " + weight + ")";
}
}
