#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define fr first
#define sc second
const ll mxn=1e5+5;
ll n,s,q,e,st[mxn],fn[mxn],cnt=0,mark[mxn];
ll par[mxn][20],bl[mxn][20],mx[mxn][20],dp[mxn],yal[mxn],ras[mxn];
vector<pair<ll,ll> >v[mxn];
void pre(ll z){
dp[z]=(mark[z])?0:1e15;
st[z]=++cnt;
for(ll i=1;i<20;i++){
par[z][i]=par[par[z][i-1]][i-1];
bl[z][i]=bl[par[z][i-1]][i-1]+bl[z][i-1];
}
for(auto i:v[z]){
if(par[z][0]!=i.fr){
bl[i.fr][0]=yal[i.sc];
ras[i.sc]=i.fr;
par[i.fr][0]=z;
pre(i.fr);
dp[z]=min(dp[z],dp[i.fr]+yal[i.sc]);
}
}
fn[z]=cnt;
}
void dfs(ll z){
mx[z][0]=dp[z];
for(ll i=1;i<20;i++){
mx[z][i]=min(mx[z][i-1],mx[par[z][i-1]][i-1]+bl[z][i-1]);
}
for(auto i:v[z]){
if(par[z][0]!=i.fr){
dfs(i.fr);
}
}
}
ll lca(ll x,ll y){
ll dis=0,res=1e15;
for(ll i=19;i>=0;i--){
if(par[x][i]==0)
continue;
if(st[par[x][i]]>st[y] || fn[par[x][i]]<fn[y]){
res=min(res,mx[x][i]+dis);
dis+=bl[x][i];
x=par[x][i];
}
}
return min(res,mx[x][0]+dis);
}
int main(){
ios::sync_with_stdio(false);
cin>>n>>s>>q>>e;
for(ll i=1;i<n;i++){
ll x,y,w;
cin>>x>>y>>yal[i];
v[x].push_back({y,i});
v[y].push_back({x,i});
}
for(ll i=1;i<=s;i++){
ll x;
cin>>x;
mark[x]=1;
}
pre(e);
dfs(e);
while(q--){
ll x,y;
cin>>x>>y;
swap(x,y);
y=ras[y];
//cout<<x<<" "<<y<<endl;
if(st[y]>st[x] || fn[y]<fn[x])
cout<<"escaped"<<'\n';
else{
if(dp[y]==1e15)
cout<<"oo"<<'\n';
else{
cout<<lca(x,y)<<'\n';
}
}
}
return 0;
}
