#include <iostream>
#include<algorithm>
#include <vector>
#define ll long long
#define fi first
#define se second
#define pb push_back
using namespace std;
const ll INF=1e18+5;
ll n, s, q, e, u, v, w;
vector<pair<pair<int, int>, int>>graph[100005];
vector<pair<int, int>>edge;
bool shop[100005];
ll dfs(int x, int p, int road, ll d){
if(x==e){
return -1;
}
ll dist=INF;
if(shop[x])
dist=d;
for(auto y : graph[x]){
if(y.se!=road && y.fi.fi!=p){
dist=min(dist, dfs(y.fi.fi, x, road, d+y.fi.se));
}
}
return dist;
}
int main()
{
//ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n >> s >> q >> e;
for(int i=1; i<n; i++){
cin >> u >> v >> w;
graph[u].pb({{v, w}, i});
graph[v].pb({{u, w}, i});
}
for(int i=0; i<s; i++){
cin >> u;
shop[u]=1;
}
while(q--){
cin >> u >> v;
ll mn=dfs(v, v, u, 0LL);
if(mn==(ll)-1)
cout << "escaped";
else if(mn==INF)
cout << "oo";
else
cout << mn;
cout << endl;
}
return 0;
}
