#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pll pair<int, int>
#define mp make_pair
#define pb push_back
#define f first
#define s second
int n,q,s,e;
vector<vector<pair<int,int>>> al(100005);
vector<bool> shop(100005, 0), inpath(100005, 0);
vector<int> ans(100005, 0),len(100005, 0),dist(100005, 1e15), dep(100005, 0), par(100005, 0);
vector<vector<pair<int,int>>> qry(100005);
void calc(int x, int pind){
for(auto [to, ind]:al[x]){
if(ind==pind)continue;
dep[ind]=dep[pind]+1;
par[to]=ind;
calc(to, ind);
dist[x]=min(dist[x], dist[to]+len[ind]);
}
if(shop[x])dist[x]=0;
}
struct node{
int s,e,m,lz,v;
node *l, *r;
node (int S,int E){
s=S,e=E,m=(s+e)/2,lz=0,v=0;
if(s!=e){
l=new node(s, m);
r=new node(m+1, e);
}
}
void prop(){
if(s==e or lz==0)return;
l->v+=lz, r->v+=lz, r->lz += lz, l->lz += lz;
lz=0;
}
void rangeadd(int S,int E, int V){
prop();
if(S<=s and e<=E){
v+=V;
lz+=V;
return;
}
prop();
if(E <= m)l->rangeadd(S, E, V);
else if(S > m)r->rangeadd(S, E, V);
else l->rangeadd(S,m, V), r->rangeadd(m+1, E, V);
v=min(l->v, r->v);
}
int rangemin(int S, int E){
prop();
if(S<=s and e<=E){
return v;
}
prop();
if(E <= m)return l->rangemin(S, E);
else if(S>m)return r->rangemin(S,E);
return min(l->rangemin(S, m), r->rangemin(m+1, E));
}
} *root;
void dfs(int x, int pind){
// enter
root->rangeadd(0, max(0ll, dep[pind]-1), len[par[x]]);
root->rangeadd(dep[pind], dep[pind], dist[x]);
//~ printf("at %lld, dep of pind is %lld, len is %lld, added to %lld, value%lld\n",
//~ x, dep[par[x]], len[par[x]], dep[pind], dist[x]);
//~ assert(pind==par[x]);
//~ for(int i=0;i<n;i++){
//~ cout<<root->rangemin(i, i)<<" ";
//~ }
//~ cout<<endl;
inpath[pind]=true;
for(auto [ind, cutind]:qry[x]){
//ans[ind]
if(inpath[cutind]){
ans[ind]=root->rangemin(dep[cutind], dep[pind]);
}
else {
ans[ind]=-1;
}
}
for(auto [to, ind]:al[x]){
if(ind==pind)continue;
dfs(to, ind);
}
root->rangeadd(0, max(0ll, dep[pind]-1), -len[par[x]]);
root->rangeadd(dep[pind], dep[pind], -dist[x]);
//~ printf("leaving %lld, dep of pind is %lld, len is %lld, minusing indiv to %lld, value%lld\n",
//~ x, dep[par[x]], len[par[x]], dep[pind], dist[x]);
inpath[pind]=false;
}
signed main(){
cin>>n>>s>>q>>e;
root=new node(0, n);
for(int i=1;i<n;i++){
int a,b,w;cin>>a>>b>>w;
len[i]=w;
al[a].pb({b, i});
al[b].pb({a, i});
}
for(int i=0;i<s;i++){
int k;cin>>k;shop[k]=true;
}
for(int i=0;i<q;i++){
int cutind, x;cin>>cutind>>x;
qry[x].pb({i, cutind});
}
calc(e, 0);
dfs(e, 0);
//~ for(int i=1;i<=n;i++){
//~ cout<<dist[i]<<" ";
//~ }cout<<endl;
for(int i=0;i<q;i++){
if(ans[i] >= 1e15){
cout<<"oo\n";
}
else if(ans[i]==-1){
cout<<"escaped\n";
}
else {
cout<<ans[i]<<"\n";
}
}
}
