#include <bits/stdc++.h>
using namespace std;
vector < pair <int , int> > adiacenta[100001];
pair < int , pair <int64_t , int64_t> > urmatorul[100001][17];
int __nod[100001][2] , adancime[100001];
int64_t minim[100001];
bool tip[100001];
void Parcurgere (const int nod)
{
minim[nod] = (tip[nod] ? 0 : INT64_MAX);
for (auto& vecin : adiacenta[nod]) {
if (vecin.first != urmatorul[nod][0].first)
{
adancime[vecin.first] = adancime[nod] + 1;
urmatorul[vecin.first][0].second.first = vecin.second;
urmatorul[vecin.first][0].first = nod;
Parcurgere(vecin.first);
if (minim[vecin.first] != INT64_MAX)
{ minim[nod] = min(minim[nod] , minim[vecin.first] + vecin.second); }
}
}
urmatorul[nod][0].second.second = minim[nod];
}
void Build (const int nod)
{
for (int exponent = 1 ; (1 << exponent) <= adancime[nod] ; exponent++)
{
urmatorul[nod][exponent].first = urmatorul[urmatorul[nod][exponent - 1].first][exponent - 1].first;
urmatorul[nod][exponent].second.first = urmatorul[nod][exponent - 1].second.first + urmatorul[urmatorul[nod][exponent - 1].first][exponent - 1].second.first;
urmatorul[nod][exponent].second.second = min(urmatorul[nod][exponent - 1].second.second , (urmatorul[urmatorul[nod][exponent - 1].first][exponent - 1].second.second == INT64_MAX ? INT64_MAX : urmatorul[urmatorul[nod][exponent - 1].first][exponent - 1].second.second + urmatorul[nod][exponent - 1].second.first));
}
for (auto& vecin : adiacenta[nod]) {
if (vecin.first != urmatorul[nod][0].first)
{ Build(vecin.first); }
}
}
pair <int , int64_t> Jump (int nod , int adancime)
{
int64_t termen = 0 , __minim = INT64_MAX;
for (int exponent = 16 ; exponent >= 0 ; exponent--) {
if (adancime & (1 << exponent))
{
if (urmatorul[nod][exponent].second.second != INT64_MAX)
{ __minim = min(__minim , urmatorul[nod][exponent].second.second + termen); }
termen += urmatorul[nod][exponent].second.first;
nod = urmatorul[nod][exponent].first;
}
}
if (minim[nod] != INT64_MAX)
{ __minim = min(__minim , minim[nod] + termen); }
return {nod , __minim};
}
int main ()
{
ios :: sync_with_stdio(false);
cin.tie(NULL); cout.tie(NULL);
int numar_noduri , special , numar_intrebari , radacina;
cin >> numar_noduri >> special >> numar_intrebari >> radacina;
for (int indice = 1 , cost ; indice < numar_noduri ; indice++)
{
cin >> __nod[indice][0] >> __nod[indice][1] >> cost;
adiacenta[__nod[indice][0]].emplace_back(__nod[indice][1] , cost);
adiacenta[__nod[indice][1]].emplace_back(__nod[indice][0] , cost);
}
while (special--)
{
int nod;
cin >> nod;
tip[nod] = true;
}
Parcurgere(radacina);
Build(radacina);
while (numar_intrebari--)
{
int indice , inceput;
cin >> indice >> inceput;
pair <int , int> muchie = {__nod[indice][0] , __nod[indice][1]};
if (adancime[muchie.first] > adancime[muchie.second])
{ swap(muchie.first , muchie.second); }
if (adancime[muchie.second] > adancime[inceput])
{ cout << "escaped\n"; continue; }
const pair <int , int64_t> candidat = Jump(inceput , adancime[inceput] - adancime[muchie.second]);
if (candidat.first != muchie.second)
{ cout << "escaped\n"; continue; }
if (candidat.second == INT64_MAX)
{ cout << "oo\n"; continue; }
cout << candidat.second << '\n';
}
return 0;
}
