#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
using namespace std;
typedef long long ll;
typedef tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update> intset;
int N,Q,E,S,a,b,w;
vector<bool> shop;
vector<ll> dp;
vector<pair<ll,ll>> lista;
vector<vector<pair<ll,ll>>> graph;
vector<vector<ll>> padre,dist,resp;
vector<int> alt;
void solve(int now,int ante){
resp[now][0]=dp[padre[now][0]]+dist[now][0];
for(int i=1;i<20;i++){
resp[now][i]=min(resp[now][i-1],resp[padre[now][i-1]][i-1]+dist[now][i-1]);
}
for(auto u:graph[now]){
if(u.first==ante){
continue;
}
solve(u.first,now);
}
}
ll dfs(int now,int ante){
if(shop[now]){
dp[now]=0;
}
for(int i=1;i<20;i++){
padre[now][i]=padre[padre[now][i-1]][i-1];
dist[now][i]=dist[now][i-1]+dist[padre[now][i-1]][i-1];
}
for(auto u:graph[now]){
if(u.first==ante){
continue;
}
alt[u.first]=alt[now]+1;
padre[u.first][0]=now;
dist[u.first][0]=u.second;
dp[now]=min(dp[now],dfs(u.first,now)+u.second);
}
return dp[now];
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
cin >> N >> S >> Q >> E;
graph.resize(N);
shop.resize(N);
alt.resize(N);
dp.assign(N,1e18);
padre.assign(N,vector<ll>(20));
lista.resize(N);
dist=resp=padre;
for(int i=1;i<N;i++){
cin >> a >> b >> w;
graph[--a].push_back({--b,w});
graph[b].push_back({a,w});
lista[i-1]={a,b};
}
while(S--){
cin >> a;
shop[--a]=true;
}
alt[--E]=0;
padre[E][0]=E;
dfs(E,-1);
solve(E,-1);
while(Q--){
cin >> a >> b;
int nododesa;
a--;
if(alt[lista[a].first]<alt[lista[a].second]){
nododesa=lista[a].second;
}else{
nododesa=lista[a].first;
}
int x=--b;
int y=nododesa;
if(alt[x]<alt[y]){
cout << "escaped\n";
continue;
}
int dif=alt[x]-alt[y];
for(int i=20;i>=0;i--){
if(dif&(1<<i)){
x=padre[x][i];
}
}
if(x==y){
//no se escapa
ll op2=1e18;
x=b;
ll op1=dp[x];
ll tempdist=0;
for(int i=20;i>=0;i--){
if(dif&(1<<i)){
op2=min(op2,tempdist+resp[x][i]);
tempdist+=dist[x][i];
x=padre[x][i];
}
}
if(min(op1,op2)==1e18){
cout << "oo\n";
}else{
cout << min(op1,op2) << "\n";
}
}else{
cout << "escaped\n";
}
}
}
