#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#include <utility>
#include <algorithm>
#include <tuple>
#include <set>
#include <functional>
enum QueryAnswer {
AnswerEscaped = -2,
AnswerInfinity = -1,
};
int gs, sh, q, dest;
std::vector<int> shops;
bool is_shop[100005];
std::vector<std::vector<std::pair<int,int>>> adj_list;
std::vector<std::tuple<int,int,int>> edges;
std::vector<std::pair<int,int>> queries[100005];
int64_t query_ans[100005];
int depth[100005];
int64_t dist[100005];
int par[100005];
int sp_tb_tour[18][200005];
int tin[100005];
int tout[100005];
int fnwk[200005];
void fnwk_add(int k, int val) {
while (k < 200005) {
fnwk[k] += val;
k += k&-k;
}
}
int fnwk_query(int pos) {
int ret = 0;
while (pos > 0) {
ret += fnwk[pos];
pos ^= pos&-pos;
}
return ret;
}
inline int fnwk_query(int l, int r) {
return fnwk_query(r) - fnwk_query(l-1);
}
int dcmp_root;
std::vector<std::vector<int>> adj_list_dcmp;
std::set<std::pair<int64_t,int>> benis_in[100005]; // inside of subtree
std::set<std::pair<int64_t,int>> benis_out[100005]; // outside of subtree
int par_dcmp[100005];
inline int highest_node(int a, int b) {
return ((depth[a]<=depth[b]) ? a : b);
}
void dfs1(int k, int p, int& timer) {
depth[k] = depth[p]+1;
par[k] = p;
++timer;
sp_tb_tour[0][timer] = k;
tin[k] = tout[k] = timer;
for (const auto& [i, w] : adj_list[k]) {
if (i!=p) {
dist[i] = dist[k]+w;
dfs1(i,k,timer);
++timer;
sp_tb_tour[0][timer] = k;
tout[k] = timer;
}
}
}
void build_sparse_table() {
for (int l = 1; l < 18; l++) {
for (int i = 1; i+(1<<l)-1 <= 2*gs-1; i++) {
sp_tb_tour[l][i] = highest_node(sp_tb_tour[l-1][i],sp_tb_tour[l-1][i+(1<<(l-1))]);
}
}
}
inline int get_lca(int a, int b) {
int l = tin[a];
int r = tin[b];
if (l>r) {
std::swap(l,r);
}
int lvl = 31-__builtin_clz(r-l+1);
return highest_node(sp_tb_tour[lvl][l],sp_tb_tour[lvl][r-(1<<lvl)+1]);
}
inline int64_t get_dist(int a, int b) {
if (!a||!b) {
return 0x3f3f3f3f3f3f3f3f;
}
return dist[a] + dist[b] - 2*dist[get_lca(a,b)];
}
void build_centroid_decomp() {
std::vector<int> sub_sz(gs+1,0);
std::vector<bool> blocked(gs+1,0);
const std::function<int(int,int)> dfs_sz = [&](int k, int p) {
sub_sz[k] = 1;
for (const auto& [i, w] : adj_list[k]) {
if (!blocked[i]&&i!=p) {
sub_sz[k] += dfs_sz(i,k);
}
}
return sub_sz[k];
};
const std::function<int(int,int,int)> dfs_centroid = [&](int k, int p, int sz) {
for (const auto& [i, w] : adj_list[k]) {
if (i!=p&&!blocked[i]&&sub_sz[i]>sz/2) {
return dfs_centroid(i,k,sz);
}
}
return k;
};
const std::function<void(int,int)> dfs_build = [&](int k, int p) {
int sz = dfs_sz(k,0);
int cen = dfs_centroid(k,0,sz);
if (p) {
//std::cout << p << " " << cen << "\n";
adj_list_dcmp[p].emplace_back(cen);
adj_list_dcmp[cen].emplace_back(p);
par_dcmp[cen] = p;
}
else {
dcmp_root = cen;
//std::cout << dcmp_root << "\n";
}
blocked[cen] = 1;
for (const auto& [i, w] : adj_list[cen]) {
if (!blocked[i]) {
dfs_build(i,cen);
}
}
};
dfs_build(1,0);
}
void decomp_add(std::set<std::pair<int64_t,int>>* benis, int node) {
int k = node;
while (k) {
benis[k].emplace(get_dist(node,k), node);
k = par_dcmp[k];
}
}
void decomp_remove(std::set<std::pair<int64_t,int>>* benis, int node) {
int k = node;
while (k) {
benis[k].erase(benis[k].lower_bound(std::pair<int64_t,int>(get_dist(node,k), node)));
k = par_dcmp[k];
}
}
int64_t decomp_query(std::set<std::pair<int64_t,int>>* benis, int node) {
int k = node;
int64_t ret = 0x3f3f3f3f3f3f3f3f;
while (k) {
ret = std::min(ret, benis[k].begin()->first + get_dist(node,k));
k = par_dcmp[k];
}
return ret;
}
void dfs_solve(int k, int p) {
for (const auto& [node, qidx] : queries[k]) {
//std::cout << k << " " << node << " " << qidx << "\n";
if (tin[k]<=tin[node]&&tout[node]<=tout[k]) {
query_ans[qidx] = decomp_query(benis_in, node);
if (is_shop[node]) {
query_ans[qidx] = 0;
}
}
else {
query_ans[qidx] = decomp_query(benis_out, node);
if (is_shop[node]) {
query_ans[qidx] = 0;
}
}
}
if (is_shop[k]) {
decomp_remove(benis_in, k);
decomp_add(benis_out, k);
}
for (const auto& [i, w] : adj_list[k]) {
if (i!=p) {
dfs_solve(i,k);
}
}
if (is_shop[k]) {
decomp_remove(benis_out, k);
decomp_add(benis_in, k);
}
}
int main() {
std::ios_base::sync_with_stdio(false);
std::cin.tie(NULL);
std::cout.tie(NULL);
std::cin >> gs >> sh >> q >> dest;
adj_list.resize(gs+1);
adj_list_dcmp.resize(gs+1);
edges.reserve(gs-1);
for (int i = 0, a, b, c; i < gs-1; i++) {
std::cin >> a >> b >> c;
edges.emplace_back(a,b,c);
adj_list[a].emplace_back(b,c);
adj_list[b].emplace_back(a,c);
}
shops.reserve(sh);
for (int i = 0, tmp; i < sh; i++) {
std::cin >> tmp;
is_shop[tmp] = 1;
shops.emplace_back(tmp);
}
{ int timer = 0; dfs1(1,0,timer); }
build_sparse_table();
for (auto& [a, b, c] : edges) {
if (depth[a]>depth[b]) {
std::swap(a,b);
}
}
/*for (int i = 1; i <= gs; i++) {
std::cout << i << " " << tin[i] << " " << tout[i] << "\n";
}*/
build_centroid_decomp();
for (int i = 1; i <= gs; i++) {
benis_in[i].emplace(0x3f3f3f3f3f3f3f3f,0);
benis_out[i].emplace(0x3f3f3f3f3f3f3f3f,0);
}
for (const auto& i : shops) {
fnwk_add(tin[i],1);
}
for (int i = 0, edge_idx, node; i < q; i++) {
std::cin >> edge_idx >> node; --edge_idx;
//queries[std::get<1>(edges[edge_idx])].emplace_back(node, i);
//std::cout << i << " " << edge_idx << " " << std::get<0>(edges[edge_idx]) << " " << std::get<1>(edges[edge_idx]) << " " << node << "\n";
if (tin[std::get<1>(edges[edge_idx])] <= tin[node] && tout[node] <= tout[std::get<1>(edges[edge_idx])]) {
if (tin[std::get<1>(edges[edge_idx])] <= tin[dest] && tout[dest] <= tout[std::get<1>(edges[edge_idx])]) {
query_ans[i] = AnswerEscaped;
}
else if (!fnwk_query(tin[std::get<1>(edges[edge_idx])], tout[std::get<1>(edges[edge_idx])])) {
query_ans[i] = AnswerInfinity;
}
else {
queries[std::get<1>(edges[edge_idx])].emplace_back(node, i);
}
}
else {
if (!(tin[std::get<1>(edges[edge_idx])] <= tin[dest] && tout[dest] <= tout[std::get<1>(edges[edge_idx])])) {
query_ans[i] = AnswerEscaped;
}
else if (!fnwk_query(1, tin[std::get<1>(edges[edge_idx])]) && !fnwk_query(tout[std::get<1>(edges[edge_idx])], 2*gs-1)) {
query_ans[i] = AnswerInfinity;
}
else {
queries[std::get<1>(edges[edge_idx])].emplace_back(node, i);
}
}
}
for (int i = 1; i <= gs; i++) {
if (is_shop[i]) {
decomp_add(benis_in,i);
}
}
dfs_solve(1,0);
/*for (int i = 1; i <= gs; i++) {
std::cout << i << "\n";
for (const auto& [a, b] : benis_in[i]) {
std::cout << a << " " << b << "\n";
}
std::cout << "\n";
}*/
for (int i = 0; i < q; i++) {
if (query_ans[i]==AnswerEscaped) {
std::cout << "escaped\n";
}
else if (query_ans[i]==AnswerInfinity||query_ans[i]>=0x3f3f3f3f3f3f3f3f) {
std::cout << "oo\n";
}
else {
std::cout << query_ans[i] << "\n";
}
}
}
