#include <bits/stdc++.h>
using namespace std;
#define IOS ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0)
#define fort(itr,map) for(auto itr = map.begin(); itr != map.end(); ++itr)
#define pb push_back
#define elif else if
#define F first
#define S second
#define all(v) v.begin(), v.end()
#define uni(v) sort(all(v)), v.erase(unique(all(v)), v.end())
#define int long long
#define err_dis(i) cout << "Dis[" << i << "] = " << dis[i] << endl;
const int MAX = 1e5 + 10;
const int INF = 1LL * 1000 * 1000 * 1000 * 1000 * 1000 * 1000;
vector<pair<int, int>> adj[MAX];
vector<int> shops;
int dis[MAX];
int n, SS, q, e;
pair<int, int> edg[MAX];
set<pair<int, int>> s;
void Dijkstra(int root, int x, int y){
for(int i = 1; i <= n; i++) dis[i] = INF;
dis[root] = 0;
s.insert({dis[root], root});
while(!s.empty()){
auto [d, v] = *s.begin();
s.erase(s.begin());
for(auto [u, w]: adj[v]){
if((u == x && v == y) || (u == y && v == x)) continue;
if(dis[u] > d + w){
s.erase({dis[u], u});
dis[u] = d + w;
s.insert({dis[u], u});
}
}
}
}
main()
{IOS;
cin >> n >> SS >> q >> e;
for(int i = 1; i < n; i++){
int x, y, w; cin >> x >> y >> w;
adj[x].pb({y, w});
adj[y].pb({x, w});
edg[i] = {x, y};
}
for(int i = 1; i <= SS; i++){
int x; cin >> x;
shops.pb(x);
}
while(q--){
int l, r; cin >> l >> r;
Dijkstra(r, edg[l].F, edg[l].S);
if(dis[e] != INF) {cout << "escaped\n"; continue;}
int mini = INF;
for(int u: shops){
mini = min(mini, dis[u]);
}
if(mini != INF) cout << mini << endl;
else cout << "oo\n";
}
}
