#include <iostream>
#include <vector>
using namespace std;
#define ll long long
#define INF 1000000000000000
vector<pair<ll, ll>> edges;
vector<vector<pair<ll, ll>>> adj;
vector<ll> minDist;
vector<ll> isShop;
vector<pair<ll, ll>> p;
vector<ll> d;
void dfs(ll st, ll par, ll dFromPar, ll depth){
d[st] = depth;
p[st] = {par, dFromPar};
if(isShop[st]) minDist[st] = 0;
for(auto i : adj[st]){
if(i.first == par) continue;
dfs(i.first, st, i.second, depth+1);
minDist[st] = min(minDist[st], minDist[i.first] + i.second);
}
}
#define nd first
#define distToNd second.first
#define ans second.second
int main(void){
// freopen("input.txt", "r", stdin);
ll N, S, Q, E;
cin>>N>>S>>Q>>E;
E--;
minDist.assign(N, INF);
adj.assign(N, {});
isShop.assign(N, 0);
p.assign(N, {INF, INF});
d.assign(N, 0);
for(ll i = 0; i<N-1; i++){
ll 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(ll i = 0; i<S; i++){
ll c; cin>>c;
c--;
isShop[c] = 1;
}
dfs(E, E, 0, 0);
vector<vector<pair<ll, pair<ll, ll>>>> lift;
lift.assign(N, vector<pair<ll, pair<ll, ll>>>(30, pair<ll, pair<ll, ll>>{INF, {INF,INF}}));
for(ll i = 0; i<N; i++){
lift[i][0] ={p[i].first, {p[i].second, min(minDist[i], minDist[p[i].first] + p[i].second)}};
}
for(ll j = 0; j<30; j++){
for(ll i = 0; i<N; i++){
auto n = lift[lift[i][j-1].first][j-1];
lift[i][j] = {n.nd, {lift[i][j-1].distToNd + n.distToNd,
min(n.ans + lift[i][j-1].distToNd, lift[i][j-1].ans)}};
}
}
for(ll i = 0; i<Q; i++){
ll destroyed, st;
cin>>destroyed>>st;
destroyed--; st--;
ll 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;}
ll tmp = st;
ll mn = minDist[st];
ll climbed = 0;
for(ll j = 29; j>=0; j--){
if((1<<j) & (d[st]-d[del])){
if(lift[tmp][j].ans<INF) mn = min(mn, lift[tmp][j].ans+climbed);
climbed += lift[tmp][j].distToNd;
tmp = lift[tmp][j].nd;
}
}
if(tmp != del) {cout<<"escaped"<<endl; continue;}
if(mn >= INF) {cout<<"oo"<<endl; continue;}
cout<<mn<<endl;
}
}
