#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define ll long long
#define all(x) (x).begin(), (x).end()
const int N = 2e5 + 100 , LOG = 20;
vector <vector <pair <int , int>>> edj;
map <pair <int , int> , int> idx;
vector <bool> vis;
bool ok = 1 , ok2 = 0;
int target ;
void dfs(int node , int nx) {
if(vis[node] || ok2) return; vis[node] = 1;
if(target == node) ok2 = 1;
for(auto [w , to] : edj[node]) {
int k = idx[{node , to}];
if(k == nx) continue;
// cout << k << ' ' << nx << '\n';
dfs(to , nx);
}
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int n , s , Q , e ; cin >> n >> s >> Q >> e; target = e;
edj = vector <vector <pair <int , int>>> (n + 1);
vector <tuple <int , int , int>> vec(n - 1);
vis = vector <bool>(n + 1, false);
for(int i = 0 ; i < n - 1 ; i ++) {
int u , v , w; cin >> u >> v >> w;
vec[i] = {u , v , w};
idx[{u , v}] = idx[{v , u}] = i + 1;
edj[u].pb({w , v});
edj[v].pb({w , u});
}
vector <int> shops(s);
for(int i = 0 ; i < s ; i ++) {
cin >> shops[i];
}
// for(int i = 1 ; i <= n ; i ++) cout << dist[i] << ' ';cout << '\n';
while( Q-- ) {
int l , r ; cin >> l >> r; ok = 1; ok2 = 0;
fill(all(vis) , 0);
dfs(r , l);
if(ok2) {
cout << "escaped\n"; continue;
}
queue <int> q;
vector <ll> dist(n + 1 , (ll) 1e18);
for(int i = 0 ; i < s ; i ++) {
q.push(shops[i]);
dist[shops[i]] = 0;
}
while(q.size()) {
int u = q.front(); q.pop();
for(auto [w , to] : edj[u]) {
int k = idx[{u , to}];
if(k == l) continue;
// cout <<
if(dist[to] > dist[u] + w) {
dist[to] = dist[u] + w;
q.push(to);
}
}
}
// cout << dist[r] << '\n';
if(dist[r] == (ll)1e18) cout << "oo\n";
else cout << dist[r] << '\n';
}
}
