#include<bits/stdc++.h>
using namespace std;
const int NMAX = 100000;
#define int long long
int nbVilles, nbMagazins, nbRequetes, destination;
struct T {
int dest, temps, iArete, premDist;
};
vector<T> chemins[NMAX];
bool magazin[NMAX];
//int trouverPlusProche()
vector<int> traceLca;
pair<int, int> posTrace[NMAX];
int iValNoeud;
int noeudVersLca[NMAX];
int lcaVersNoeud[NMAX];
int profondeur[NMAX];
void parcours(int noeud, int anc)
{
if(anc == -1)
{
profondeur[noeud] = 1;
}
else
profondeur[noeud] = profondeur[anc] +1;
iValNoeud++;
int valActu = iValNoeud;
noeudVersLca[noeud] = valActu;
lcaVersNoeud[valActu] = noeud;
posTrace[valActu].first = traceLca.size();
posTrace[valActu].second = traceLca.size();
traceLca.push_back(valActu);
for(auto pro : chemins[noeud])
{
if(pro.dest == anc) continue;
parcours(pro.dest, noeud);
posTrace[valActu].second = traceLca.size();
traceLca.push_back(valActu);
}
}
int arbreMin[NMAX*3];
pair<int, int> debFin[NMAX*3];
const int INFINI = 1e15;
int construire(int noeud, int deb, int fin)
{
debFin[noeud] = {deb, fin};
if(deb == fin-1) return arbreMin[noeud] = traceLca[deb];
int mil = (deb+fin)/2;
return arbreMin[noeud] = min(construire(noeud*2, deb, mil), construire(noeud*2+1, mil, fin));
}
int trouverMin(int noeud, int deb, int fin)
{
// cout << "debArbre " << noeud << endl;
if((debFin[noeud].first >= deb) && (debFin[noeud].second <= fin))
{
// cout << noeud << " " << arbreMin[noeud] << "\n";;
return arbreMin[noeud];
}
if((debFin[noeud].first >= fin) || (debFin[noeud].second <= deb)) {
// cout << noeud << " " << INFINI << "\n";;
return INFINI;
}
int a = min(trouverMin(noeud*2, deb, fin), trouverMin(noeud*2+1, deb, fin));
// cout << noeud << " " << a << "\n";;
return a;
}
pair<int, int> arrays[NMAX];
pair<int, int> plusHaut(int iArray)
{
int a = arrays[iArray].first, b = arrays[iArray].second;
if(profondeur[a] < profondeur[b]) return {a, b};
return {b, a};
}
bool liaison(int noeud, int ancetre)
{
int noeudLca = noeudVersLca[noeud], ancetreLca = noeudVersLca[ancetre];
int posNoeud = posTrace[noeudLca].first;
int debA = posTrace[ancetreLca].first, finA = posTrace[ancetreLca].second;
// cout << noeud << " a " << ancetre << ' ' << debA << " " << finA << " : " << posNoeud << endl;
if((debA <= posNoeud) && (finA >= posNoeud)) return true;
return false;
}
int lca(int noeud1, int noeud2)
{
// cout << noeud1 << " " << noeud2 << endl;
noeud1 = noeudVersLca[noeud1];
noeud2 = noeudVersLca[noeud2];
int pos1 = posTrace[noeud1].first;
int pos2 = posTrace[noeud2].first;
// cout << noeud1 << " : " << pos1 << " " << noeud2 << " : " << pos2 << endl;
int rep = trouverMin(1, min(pos1, pos2), max(pos1, pos2)+1);
// cout << "rep lca : " << rep << endl;
return lcaVersNoeud[rep];
}
signed main()
{
ios::sync_with_stdio(false);
cin.tie(0);
iValNoeud = -1;
cin >> nbVilles >> nbMagazins >> nbRequetes >> destination;
--destination;
for(int i = 0; i < nbVilles; i++) posTrace[i] = {-1, -1};
for(int i = 0; i < nbVilles-1; i++)
{
int a, b, t;
cin >> a >> b >> t;
--a;
--b;
chemins[a].push_back({b, t, i, 0});
chemins[b].push_back({a, t, i, 0});
arrays[i] = {a, b};
}
for(int i = 0; i < nbMagazins; i++)
{
int a;
cin >> a;
--a;
magazin[a] = true;
}
parcours(0, -1);
// for(int i = 0; i < nbVilles; i++) cout << lcaVersNoeud[i] << " ";
// for(int i : traceLca) cout << lcaVersNoeud[i]+1 << " ";
// cout << endl;
construire(1, 0, traceLca.size());
for(int iRequete = 0; iRequete < nbRequetes; iRequete++)
{
//lca dep arrivee + detection si empeche est un ancetre, comparaison des profondeurs
int routeFerme, depart;
cin >> routeFerme >> depart;
--routeFerme;
--depart;
// cout << "deb" << endl;
int interditDePasse = plusHaut(routeFerme).first, autre = plusHaut(routeFerme).second;
bool surChemin = ((liaison(depart, interditDePasse) && (liaison(depart, autre)) && (profondeur[depart] > profondeur[interditDePasse]))
|| (liaison(destination, interditDePasse) && (liaison(destination, autre)) && (profondeur[destination] > profondeur[interditDePasse])));//
// cout << "deb " << depart << " " << destination << " : " << routeFerme << endl;
// cout << surChemin << " " << lca(depart, destination) << endl;
if(surChemin && (profondeur[lca(depart, destination)] <= profondeur[interditDePasse]))
{
cout << 0 << "\n";
}
else
cout << "escaped" << "\n";
}
// trouverPlusProche(0, -1);
}
