#include <bits/stdc++.h>
#define int long long
#define ff first
#define ss second
#define pb push_back
#define all(x) x.begin(),x.end()
using namespace std;
const int N=1e5+5;
vector <pair <int,int > > g[N];
int d[N],par[N],jmp[N][20],dis[N],shop[N],dis2[N],jmp_mn[N][20];
void dfs(int v,int p){
par[v]=p;
for(auto to : g[v]){
if(to.ff!=p){
dis[to.ff]=dis[v]+to.ss;
d[to.ff]=d[v]+1;
dfs(to.ff,v);
}
}
}
void dfs2(int v,int p){
for(auto to : g[v]){
if(to.ff!=p)dfs2(to.ff,v);
}
if(shop[v])dis2[v]=dis[v];
dis2[p]=min(dis2[p],dis2[v]);
}
int lca(int a,int b){
if(d[a]<d[b])swap(a,b);
for(int i=19;i>=0;i--){
if(d[jmp[a][i]]>=d[b]){
a=jmp[a][i];
}
}
if(a==b)return a;
for(int i=19;i>=0;i--){
if(jmp[a][i]!=jmp[b][i]){
a=jmp[a][i];
b=jmp[b][i];
}
}
return par[a];
}
signed main(){
ios_base::sync_with_stdio();
cin.tie(0);cout.tie(0);
int n,s,q,e;
cin>>n>>s>>q>>e;
vector <int> mag(s),a(n),b(n),c(n);
for(int i=0;i<n-1;i++){
cin>>a[i]>>b[i]>>c[i];
g[a[i]].pb({b[i],c[i]});
g[b[i]].pb({a[i],c[i]});
}
dfs(e,0);
for(int i=0;i<s;i++){
cin>>mag[i];
shop[mag[i]]=1;
}
for(int i=1;i<=n;i++){
dis2[i]=1e18;
}
dfs2(e,0);
for(int i=1;i<=n;i++){
if(dis2[i]!=1e18)dis2[i]-=2*dis[i];
}
par[e]=e;
for(int i=1;i<=n;i++){
jmp[i][0]=par[i];
jmp_mn[i][0]=dis2[par[i]];
}
for(int j=1;j<20;j++){
for(int i=1;i<=n;i++){
jmp[i][j]=jmp[jmp[i][j-1]][j-1];
jmp_mn[i][j]=min(jmp_mn[i][j-1],jmp_mn[jmp[i][j-1]][j-1]);
}
}
while(q--){
int ind,x;
cin>>ind>>x;
ind--;
int u=a[ind];
int v=b[ind];
if(d[u]<d[v])swap(u,v);
if(lca(u,x)!=u)cout<<"escaped\n";
else{
int ans=dis[x],mn=dis2[x];
for(int i=19;i>=0;i--){
if(d[jmp[x][i]]>=d[u]){
mn=min(mn,jmp_mn[x][i]);
x=jmp[x][i];
}
}
mn=min(mn,dis2[x]);
if(mn==1e18)cout<<"oo\n";
else cout<<ans+mn<<"\n";
}
}
}
/*
*/
