#include <bits/stdc++.h>
#define N 100001
#define INF 1e18
#define LOG 18
#define fi first
#define se second
#define ll long long
using namespace std;
vector<pair<ll,ll>> vec[N];
pair<ll,ll> edg[N];
ll shop[N],weight[N],dist[N],closest[N],in[N],out[N],io=0,par[N][LOG],best[N][LOG],d=0;
//compute dist
//compute par
//compute in/out
//compute closest
void dfs(ll u, ll p){
closest[u]=(shop[u]? 0:INF);
in[u]= ++io;
par[u][0]=p;
for(ll i=1;i<LOG;i++){
par[u][i]=par[par[u][i-1]][i-1];
for(auto dub:vec[u]){
ll v=dub.fi,w=dub.se;
if(v!=p){
dist[v]=dist[u]+w;
dfs(v,u);
closest[u]=min(closest[u],closest[v]+w);
}
}
}
out[u]=io;
}
//compute best paths
void dfs2(ll u, ll p){
best[u][0]=(dist[u]-dist[p])+closest[p];
for(ll i=1;i<LOG;i++){
d=dist[u]-dist[par[u][i-1]];
best[u][i]=min(best[u][i-1],best[par[u][i-1]][i-1]+d);
}
for(auto dub:vec[u]){
if(dub.fi!=p){
dfs2(dub.fi,u);
}
}
}
bool ispar(ll u, ll v){
if(in[u]<=in[v]&&out[u]>=out[v]) return 1;
return 0;
}
ll getbest(ll r, ll u){
ll cur=closest[r],d=0;
for(ll i=LOG-1;i>=0;i--){
ll jump=par[r][i];
if(!ispar(jump,u)){//cout<<'!';
cur=min(cur,d+best[r][i]);
d+=dist[r]-dist[jump];
r=jump;
}
}
return cur;
}
int main()
{
//ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
//fill(closest,closest+N,INF);
//for(ll i=0;i<N;i++)fill(best[i],best[i]+LOG,INF);
ll n=0,s=0,q=0,e=0,a=0,b=0,w=0;
cin>>n>>s>>q>>e;
for(ll i=0;i<n-1;i++){
cin>>a>>b>>w;
vec[a].push_back({b,w});
vec[b].push_back({a,w});
edg[i]={a,b};
}
for(ll i=0;i<s;i++){
cin>>a;
shop[a]=1;
}
dfs(e,e);
dfs2(e,e);
for(ll i=0;i<q;i++){
cin>>a>>b;
ll u=edg[a-1].first;
ll v=edg[a-1].se;
if(dist[u]<dist[v])swap(u,v);//child node first, parent second
if(ispar(u,b)){
ll rez=getbest(b,v);
if(rez==INF)cout<<"oo\n";
else cout<<rez<<'\n';
}
else cout<<"escaped\n";
}
//for(ll y:in)cout<<y<<' ';
//cout<<'\n';
//for(ll y:out)cout<<y<<' ';
return 0;
}
//5 2 3 1 1 2 3 1 3 2 3 4 1 3 5 2 2 4 2 2 2 5 4 5
