#include <bits/stdc++.h>
#define ll long long
#define ii pair<ll,ll>
#define iii pair<ll,pair<ll,ll>>
#define fi first
#define se second
using namespace std;
const int N=1e5+5;
const ll inf=1e18;
vector<ii>v[N];
vector<iii>v2(N);
int n,s,q,e;
int a2[N];
int a1[N];
ll a4[N];
int p[N];
int a3[N];
ll dp[N];
vector<iii>v1(N);
int f(int x){
if(x==p[x]) return x;
return p[x]=f(p[x]);
}
void f1(int x,int y){
int x1=f(x);
int y1=f(y);
if(x1!=y1){
p[x1]=y1;
}
}
void dick(){
priority_queue<ii,vector<ii>,greater<ii>>q;
for(int i=1;i<=s;i++){
dp[a2[i]]=0;
q.push({dp[a2[i]],a2[i]});
}
while(!q.empty()){
ll s1=q.top().fi;
int node=q.top().se;
q.pop();
if(s1>dp[node]) continue;
for(auto x:v[node]){
int node1=x.fi;
ll s2=x.se;
if(dp[node1]>dp[node]+s2){
dp[node1]=dp[node]+s2;
q.push({dp[node1],node1});
}
}
}
}
void dick1(int s2){
priority_queue<ii,vector<ii>,greater<ii>>q;
q.push({dp[s2],s2});
while(!q.empty()){
ll s1=q.top().fi;
int node=q.top().se;
q.pop();
if(s1>dp[node]) continue;
for(auto x:v[node]){
int node1=x.fi;
ll s2=x.se;
if(dp[node1]>dp[node]+s2){
dp[node1]=dp[node]+s2;
q.push({dp[node1],node1});
}
}
}
}
int main()
{
ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
cin >>n >>s >>q >>e;
for(int i=1;i<=n;i++){
p[i]=i;
}
for(int i=1;i<=n-1;i++){
int x,y,w;
cin >>x >>y>>w;
v2[i]={x,{y,w}};
}
for(int i=1;i<=s;i++){
cin >> a2[i];
}
for(int i=1;i<=q;i++){
int x,y;
cin >>x >>y;
v1[i]={x,{y,i}};
a3[x]=1;
}
for(int i=1;i<=n;i++){
dp[i]=inf;
}
for(int i=1;i<=n-1;i++){
if(a3[i]==0){
v[v2[i].fi].push_back({v2[i].se.fi,v2[i].se.se});
v[v2[i].se.fi].push_back({v2[i].fi,v2[i].se.se});
f1(v2[i].fi,v2[i].se.fi);
}
}
dick();
if(f(e)==f(v1[q].se.fi)) a4[q]=inf;
else{
if(dp[v1[q].se.fi]==inf) a4[q]=-inf;
else a4[q]=dp[v1[q].se.fi];
}
int node=v2[v1[q].fi].fi,node1=v2[v1[q].fi].se.fi;
ll w=v2[v1[q].fi].se.se;
f1(node,node1);
v[node].push_back({node1,w});
v[node1].push_back({node,w});
dick();
dick1(node);
dick1(node1);
for(int i=q-1;i>=1;i--){
if(f(e)==f(v1[i].se.fi)){
a4[i]=inf;
}
else{
if(dp[v1[i].se.fi]==inf){
a4[i]=-inf;
}
else{
a4[i]=dp[v1[i].se.fi];
}
}
int node=v2[v1[i].fi].fi;
int node1=v2[v1[i].fi].se.fi;
ll w=v2[v1[i].fi].se.se;
v[node].push_back({node1,w});
v[node1].push_back({node,w});
f1(node,node1);
dick();
dick1(node);
dick1(node1);
}
for(int i=1;i<=q;i++){
if(a4[i]==inf) cout << "escaped" << "\n";
else if(a4[i]==-inf) cout << "oo" << "\n";
else cout << a4[i] << "\n";
}
return 0;
}
