#include <bits/stdc++.h>
#define raya() cout << endl << "====================================" << endl
#define dbg(x) cerr << #x << ": " << x << endl;
#define dbgv(v) cerr << #v << ": "; for(auto &el : v) cerr << el << " "; cerr << '\n';
#define INFINITY 1e8
using namespace std;
using ll = long long;
int n, s, q, e;
int lg = 5;
vector<vector<pair<int, int>>> arr;
vector<vector<int>> up, min_shop;
vector<int> dp, depth, distances;
unordered_set<int> shops;
int lca(int a, int b);
int calc_distance(int a, int b){
return distances[a] + distances[b] - 2 * distances[lca(a, b)];
}
void dfs_min_shop(int curr, int prev, int weight){
min_shop[curr][0] = min(dp[curr], dp[prev] + weight);
for(int i = 1; i <= lg; i++){
min_shop[curr][i] = min({
min_shop[up[curr][i - 1]][i - 1] + calc_distance(curr, up[curr][i - 1]),
min_shop[curr][i - 1]
});
}
for(auto &x : arr[curr]){
if(x.first != prev) dfs_min_shop(x.first, curr, x.second);
}
}
void dfs_prin(int curr, int prev = -1, int weight = 0){
if(shops.count(curr)){
dp[curr] = 0;
}
up[curr][0] = prev;
distances[curr] = distances[prev] + weight;
for(int i = 1; i <= lg; i++){
up[curr][i] = up[up[curr][i - 1]][i - 1];
}
for(auto &i : arr[curr]){
if(i.first == prev) continue;
depth[i.first] = depth[curr] + 1;
dfs_prin(i.first, curr, i.second);
dp[curr] = min(dp[curr], dp[i.first] + i.second);
}
}
int lca(int a, int b){
if(depth[a] > depth[b]){
swap(a, b);
}
int dif = depth[b] - depth[a];
for(int i = lg; i >= 0; i--){
if(dif & 1 << i){
b = up[b][i];
}
}
if(a == b){
return a;
}
for(int i = lg; i >= 0; i--){
if(up[a][i] != up[b][i]){
a = up[a][i];
b = up[b][i];
}
}
return up[a][0];
}
void solve(){
cin >> n >> s >> q >> e;
e--;
vector<pair<int, int>> roads;
arr.assign(n, vector<pair<int, int>>());
dp.assign(n, INFINITY);
up.assign(n, vector<int>(lg + 1));
depth.assign(n, 0);
distances.assign(n, 0);
min_shop.assign(n, vector<int>(lg + 1));
for(int i = 0; i < n - 1; i++){
int a, b, c;
cin >> a >> b >> c;
a--;
b--;
arr[a].push_back({b, c});
arr[b].push_back({a, c});
roads.push_back({a, b});
}
for(int i = 0; i < s; i++){
int aux;
cin >> aux;
aux--;
shops.insert(aux);
}
dfs_prin(e, e, 0);
dfs_min_shop(e, e, 0);
while(q--){
int p, r;
cin >> p >> r;
p--;
r--;
int father;
if(depth[roads[p].first] > depth[roads[p].second]){
father = roads[p].first;
} else {
father = roads[p].second;
}
if(lca(father, r) != father){
cout << "escaped\n";
} else {
int ans = INFINITY;
int dis = depth[r] - depth[father];
for(int i = 0; i <= lg; i++){
if(dis & (1 << i)){
ans = min(min_shop[r][i], ans);
r = up[r][i];
}
}
if(ans >= INFINITY){
cout << "oo\n";
continue;
}
cout << ans << '\n';
}
}
}
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
solve();
}
