#include <bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define pb push_back
using namespace std;
const ll N=1e5+5;
const ll INF=1e18;
vector<pair<ll,ll>> g[N];
vector<pair<ll,ll>> roads;
ll S[N];
ll ns,e,top;
void dfs(ll v, ll p, ll d, ll ban){
if(v==top) e=1;
if(S[v]) ns=min(ns,d);
pair<ll,ll> ro=roads[ban];
ll a=ro.fi,b=ro.se;
for(auto u : g[v]){
if(u.fi==p) continue;
if((u.fi==a && v==b) || (u.fi==b && v==a)) continue;
dfs(u.fi,v,d+u.se,ban);
}
return;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
ll n,s,q;
cin>>n>>s>>q>>top;
for(ll i=0; i<n-1; i++){
ll a,b,w;
cin>>a>>b>>w;
g[a].pb({b,w});
g[b].pb({a,w});
roads.pb({a,b});
}
for(ll i=0; i<s; i++){
ll a; cin>>a;
S[a]=1;
}
for(ll i=0; i<q; i++){
ll ban,r;
cin>>ban>>r;
e=0;
ns=INF;
dfs(r,r,0,ban-1);
if(e) cout<<"escaped\n";
else if(ns!=INF) cout<<ns<<'\n';
else cout<<"oo\n";
}
return 0;
}
