#include<bits/stdc++.h>
using namespace std;
struct yal{
long long u,v,w,bache;
long long getad(long long fu){
long long ret=(fu^u^v);
return ret;
}
};
long long inf=1e17;
struct flca{
long long dis,wi,mina;
flca(){
mina=inf;
dis=0;
wi=0;
}
};
const long long maxn=100000+5;
vector<yal>alled;
vector<vector<long long>>adj;
long long n,s,rishe,q;
vector<long long>dis;
pair<long long,long long>stf[maxn];
long long para[maxn];
flca lca[20][maxn];
long long timea=0;
void dfs(long long u,long long par=0,long long ind=0){
timea++;
stf[u].first=timea;
if(u!=rishe){
para[u]=ind;
alled[ind].bache=u;
}
for(auto x:adj[u]){
long long y=alled[x].getad(u);
if(y!=par){
dfs(y,u,x);
dis[u]=min(dis[u],dis[y]+alled[x].w);
}
}
stf[u].second=timea;
}
flca merge(flca a,flca b){
flca c;
c.dis=a.dis+b.dis;
c.wi=b.wi;
c.mina=min(a.mina,b.mina+a.dis);
return c;
}
void callca(){
for(long long i=0;i<20;i++){
for(long long j=1;j<=n;j++){
if(i==0){
if(j==rishe){
continue;
}
//if(i==0&&j==5){
// cout<<" what "<<alled[para[j]].w<<"\n";
// }
lca[i][j].dis=alled[para[j]].w;
lca[i][j].wi=alled[para[j]].getad(j);
lca[i][j].mina=alled[para[j]].w+dis[lca[i][j].wi];
continue;
}
lca[i][j]=merge(lca[i-1][j],lca[i-1][lca[i-1][j].wi]);
}
}
}
void solve(long long ind,long long v){
long long u=alled[ind].bache;
if(stf[u].first<=stf[v].first&&stf[u].second>=stf[v].second){
flca now;
now.dis=0;
now.wi=v;
now.mina=dis[v];
for(long long i=19;i>=0;i--){
if(lca[i][v].wi==0){
continue;
}
if(stf[lca[i][v].wi].first<=stf[u].first&&stf[lca[i][v].wi].second>=stf[u].second){
continue;
}
now=merge(now,lca[i][v]);
v=now.wi;
}
//cout<<v<<" "<<u<<" asd \n";
if(u!=v){
now=merge(now,lca[0][v]);
}
if(now.mina==inf){
cout<<"oo\n";
}
else{
cout<<now.mina<<"\n";
}
}
else{
cout<<"escaped\n";
}
}
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin>>n>>s>>q>>rishe;
alled.resize(n-1);
adj.resize(n+1);
dis.resize(n+1,inf);
for(long long i=0;i<n-1;i++){
cin>>alled[i].u>>alled[i].v>>alled[i].w;
adj[alled[i].u].push_back(i);
adj[alled[i].v].push_back(i);
}
for(long long i=0;i<s;i++){
long long d;
cin>>d;
dis[d]=0;
}
dfs(rishe);
callca();
for(long long i=0;i<q;i++){
long long ind,u;
cin>>ind>>u;
ind--;
solve(ind,u);
}
}
