#include<bits/stdc++.h>
#include<unordered_set>
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
#define PI 3.141592653
#define rep(i,a,b) for(int i = a; i<int(b);++i)
#define rrep(i,a,b) for(int i = a; i>int(b);--i)
#define all(v) v.begin(),v.end()
#define trav(a, x) for(auto& a : x)
typedef long long ll;
const long long inf = 1e15;
using namespace std;
void printint(vector < ll > vec)
{
for (auto a : vec) {
cout << a << " ";
}
cout << endl;
}
void printstr(vector < string > vec)
{
for (auto a : vec) {
cout << a << endl;
}
}
void printchar(vector < char > vec)
{
for (auto a : vec) {
cout << a;
}
cout << endl;
}
void print2d(vector < vector < ll >> vec)
{
for (int i = 0; i < vec.size(); i++) {
printint(vec[i]);
}
cout << endl;
}
void printmap(map<int, long double> myMap) {
for (auto it = myMap.cbegin(); it != myMap.cend(); ++it)
{
std::cout << it->first << " ";
cout << it->second << " ";
}
}
void print2dchar(vector < vector < char >> vec)
{
for (auto a : vec) {
printchar(a);
}
cout << endl;
}
bool sortcol(const vector<int>& v1,
const vector<int>& v2) {
return v1[1] < v2[1];
}
void printsetint(set<ll> s) {
for (auto it = s.begin(); it != s.end(); ++it) {
cout << *it;
}
}
void printsetpairint(set<pair<int, int>> s) {
for (auto it = s.begin(); it != s.end(); ++it) {
pair<int, int> cur = *it;
cout << cur.first << " " << cur.second;
}
cout << endl;
}
void printsetstring(set<string> s) {
for (auto it = s.begin(); it != s.end(); ++it) {
cout << *it << endl;
}
}
struct MaxTree {
typedef int T;
static constexpr T unit = INT_MIN;
T f(T a, T b) { return max(a, b); } // (any associative fn)
vector<T> s; int n;
MaxTree(int n = 0, T def = unit) : s(2 * n, def), n(n) {}
void update(int pos, T val) {
for (s[pos += n] = val; pos /= 2;)
s[pos] = f(s[pos * 2], s[pos * 2 + 1]);
}
T query(int b, int e) { // query [b, e)
T ra = unit, rb = unit;
for (b += n, e += n; b < e; b /= 2, e /= 2) {
if (b % 2) ra = f(ra, s[b++]);
if (e % 2) rb = f(s[--e], rb);
}
return f(ra, rb);
}
};
struct MinTree {
typedef int T;
static constexpr T unit = INT_MAX;
T f(T a, T b) { return min(a, b); } // (any associative fn)
vector<T> s; int n;
MinTree(int n = 0, T def = unit) : s(2 * n, def), n(n) {}
void update(int pos, T val) {
for (s[pos += n] = val; pos /= 2;)
s[pos] = f(s[pos * 2], s[pos * 2 + 1]);
}
T query(int b, int e) { // query [b, e)
T ra = unit, rb = unit;
for (b += n, e += n; b < e; b /= 2, e /= 2) {
if (b % 2) ra = f(ra, s[b++]);
if (e % 2) rb = f(s[--e], rb);
}
return f(ra, rb);
}
};
vector<vector<pair<ll,ll>>> tree;
vector<vector<pair<ll,ll>>> g;
vector<ll> occurences;
vector<pair<ll, ll>> when;
void dfs(ll cur) {
when[cur].first = occurences.size();
occurences.push_back(cur);
trav(v, tree[cur]) dfs(v.first);
when[cur].second = occurences.size();
occurences.push_back(cur);
}
int main()
{
cin.sync_with_stdio(false);
ll n,s,Q,e;
cin >> n>>s>>Q>>e;
g.resize(n + 1);
tree.resize(n + 1);
when.resize(n + 1);
vector<pair<ll,ll>>edges(n);
vector<ll> parents(n + 1);
rep(i, 1, n) {
ll a, b,w;
cin >> a >> b>>w;
edges[i] = make_pair(a, b);
g[a].emplace_back(b,w);
g[b].emplace_back(a,w);
}
vector<ll> is_shop(n + 1);
rep(i, 0, s) {
ll a;
cin >> a;
is_shop[a] = true;
}
vector<bool> visitedChild(n + 1);
queue<ll> q;
q.push(e);
while (!q.empty()) {
ll cur = q.front();
q.pop();
visitedChild[cur] = true;
rep(i, 0, g[cur].size()) {
ll v = g[cur][i].first;
ll w = g[cur][i].second;
if (!visitedChild[v]) {
tree[cur].emplace_back(v,w);
parents[v] = cur;
q.push(v);
}
}
}
if (s == n) {
dfs(e);
rep(i, 0, Q) {
ll a, b;
cin >> a >> b;
ll parent;
if (parents[edges[a].first] == edges[a].second) {
parent = edges[a].first;
}
else if (parents[edges[a].second] == edges[a].first) {
parent = edges[a].second;
}
else cout << "cringe" << endl;
if (when[b].first >= when[parent].first && when[b].first <= when[parent].second) {
cout << 0 << endl;
}
else cout << "escaped" << endl;
}
}
else {
rep(i, 0, Q) {
ll a, b;
cin >> a >> b;
queue<ll> bfs;
ll dist = inf;
if (is_shop[b])dist = 0;
vector<ll> dists(n + 1,-1);
dists[b] = 0;
bfs.push(b);
while(!bfs.empty()) {
ll cur = bfs.front();
bfs.pop();
trav(v, g[cur]) {
if (dists[v.first]==-1) {
if (make_pair(v.first, cur) != edges[a] && make_pair(cur, v.first) != edges[a]) {
bfs.push(v.first);
dists[v.first] = dists[cur] + v.second;
if (is_shop[v.first])dist = min(dist, dists[v.first]);
}
}
}
}
if (dists[e] != -1) {
cout << "escaped" << endl;
}
else {
if (dist == inf) {
cout << "oo" << endl;
}
else cout << dist << endl;
}
}
}
return 0;
}
