//package ojuz;
import java.io.*;
import java.util.*;
public class valley {
public static final long inf = 1_000_000_000_000_000_000L;
public static Graph g;
public static long[][] dist, shops;
public static int[][] parents;
public static long[] shopSingle;
public static int[] depth;
public static void main(String[] args) throws IOException {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(System.out));
String[] first = reader.readLine().split(" ");
int n = Integer.parseInt(first[0]), s = Integer.parseInt(first[1]), q = Integer.parseInt(first[2]), e = Integer.parseInt(first[3]) - 1;
g = new Graph(n, 2 * n - 2);
depth = new int[n];
int log = 32 - Integer.numberOfLeadingZeros(n - 1);
dist = new long[log][n];
parents = new int[log][n];
shopSingle = new long[n];
shops = new long[log][n];
dist[0][e] = 0;
Arrays.fill(shopSingle, inf);
for (int i = 1; i < n; i++) {
String[] edge = reader.readLine().split(" ");
int a = Integer.parseInt(edge[0]) - 1, b = Integer.parseInt(edge[1]) - 1, w = Integer.parseInt(edge[2]);
g.put(a, b, w);
}
for (int i = 0; i < s; i++) {
shopSingle[Integer.parseInt(reader.readLine()) - 1] = 0;
}
dfs(e, -1, 0);
parents[0][e] = e;
for (int i = 0; i < n; i++) shops[0][i] = Math.min(shopSingle[i], shopSingle[parents[0][i]] + dist[0][i]);
for (int i = 1; i < log; i++) {
for (int j = 0; j < n; j++) {
shops[i][j] = Math.min(shops[i - 1][j], shops[i - 1][parents[i - 1][j]] + dist[i - 1][j]);
dist[i][j] = dist[i - 1][j] + dist[i - 1][parents[i - 1][j]];
parents[i][j] = parents[i - 1][parents[i - 1][j]];
}
}
for (int i = 0; i < q; i++) {
String[] query = reader.readLine().split(" ");
int edge = Integer.parseInt(query[0]) - 1, point = Integer.parseInt(query[1]) - 1;
int a = g.edges[edge * 2][0], b = g.edges[edge * 2][3];
if (depth[b] > depth[a]) a = b;
int diff = depth[point] - depth[a];
if (diff < 0) {
writer.write("escaped");
writer.newLine();
continue;
}
long minDist = shopSingle[point];
long lifted = 0;
for (int j = log - 1; j >= 0; j--) {
if ((1 << j) <= diff) {
minDist = Math.min(minDist, lifted + shops[j][point]);
lifted += dist[j][point];
point = parents[j][point];
diff -= (1 << j);
}
}
if (point != a) writer.write("escaped");
else if (minDist == inf) writer.write("oo");
else writer.write(String.valueOf(minDist));
writer.newLine();
}
writer.flush();
}
public static void dfs(int v, int p, int d) {
depth[v] = d;
parents[0][v] = p;
for (int i = g.head[v]; i != -1; i = g.edges[i][1]) {
int child = g.edges[i][0];
if (child != p) {
dfs(child, v, d + 1);
dist[0][child] = g.edges[i][2];
shopSingle[v] = Math.min(shopSingle[v], shopSingle[child] + g.edges[i][2]);
}
}
}
static class Graph {
public final int[][] edges;
public final int[] head;
public int ptr;
public Graph(int n, int m) {
this.edges = new int[m][4];
this.head = new int[n];
Arrays.fill(head, -1);
}
public void add(int a, int b, int w) {
edges[ptr][0] = b;
edges[ptr][1] = head[a];
edges[ptr][2] = w;
edges[ptr][3] = a;
head[a] = ptr++;
}
public void put(int a, int b, int w) {
add(a, b, w);
add(b, a, w);
}
}
}
