#include <iostream>
#include <vector>
using namespace std;
vector<pair<int, int>> edges;
vector<vector<pair<int, int>>> adj;
vector<int> minDist;
vector<int> isShop;
vector<pair<int, int>> p;
vector<int> d;
int t = 0;
void dfs(int st, int par, int dFromPar, int depth){
d[st] = depth;
p[st] = {par, dFromPar};
if(isShop[st]) minDist[st] = 0;
t++;
for(auto i : adj[st]){
if(i.first == par) continue;
dfs(i.first, st, i.second, depth+1);
if(minDist[st] == -1 && minDist[i.first]!=-1) minDist[st] = i.second + minDist[i.first];
if(minDist[i.first] != -1) minDist[st] = min(minDist[st], i.second + minDist[i.first]);
}
t++;
}
int main(void){
// freopen("input.txt", "r", stdin);
int N, S, Q, E;
cin>>N>>S>>Q>>E;
E--;
minDist.assign(N, -1);
adj.assign(N, {});
isShop.assign(N, 0);
p.assign(N, {-1, -1});
d.assign(N, 0);
t = 0;
for(int i = 0; i<N-1; i++){
int A, B, W;
cin>>A>>B>>W;
A--, B--;
adj[A].push_back({B, W});
adj[B].push_back({A, W});
edges.push_back({A, B});
}
for(int i = 0; i<S; i++){
int c; cin>>c;
c--;
isShop[c] = 1;
}
dfs(E, E, 0, 0);
vector<vector<pair<int, pair<int, int>>>> lift;
lift.assign(N, vector<pair<int, pair<int, int>>>(30, pair<int, pair<int, int>>{-1, {-1, -1}}));
for(int i = 0; i<N; i++){
lift[i][0] ={p[i].first, {p[i].second, min(minDist[i], minDist[p[i].first] + p[i].second)}};
if(minDist[i] == -1) lift[i][0].second.second = minDist[p[i].first] + p[i].second;
if(minDist[p[i].first] == -1) lift[i][0].second.second = minDist[i];
}
for(int j = 1; j<30; j++){
for(int i = 0; i<N; i++){
auto n = lift[lift[i][j-1].first][j-1];
lift[i][j] = {n.first, {lift[i][j-1].second.first + n.second.first,
min(n.second.second + lift[i][j-1].second.first, lift[i][j-1].second.second)}};
if(n.second.second == -1 && lift[i][j-1].second.second == -1) lift[i][j].second.second = -1;
if(n.second.second == -1) lift[i][j].second.second = lift[i][j-1].second.second;
if(lift[i][j-1].second.second == -1) lift[i][j].second.second = n.second.second + lift[i][j-1].second.first;
}
}
for(int i = 0; i<Q; i++){
int destroyed, st;
cin>>destroyed>>st;
destroyed--; st--;
int del = edges[destroyed].second;
if(edges[destroyed].first != p[edges[destroyed].second].first) del = edges[destroyed].first;
if(isShop[st]) {cout<<0<<endl; continue;}
if(d[del] > d[st]) {cout<<"escaped"<<endl; continue;}
int tmp = st;
int mn = 2000000000;
int climbed = 0;
for(int j = 29; j>=0; j--){
if((1<<j) & (d[st]-d[del])){
climbed += lift[tmp][j].second.first;
tmp = lift[tmp][j].first;
if(lift[tmp][j].second.second!=-1) mn = min(mn, lift[tmp][j].second.second+climbed);
}
}
if(tmp != del) {cout<<"escaped"<<endl; continue;}
if(mn == 2000000000) {cout<<"oo"<<endl; continue;}
cout<<mn<<endl;
}
}
