#include <bits/stdc++.h>
using namespace std;
struct road {
int v1, v2;
};
using ll = long long;
vector<road> roads;
vector<vector<pair<int, int>>> adj(100005);
ll dist[100005][2];
int shop_node[100005][2];
int tin[100005], tout[100005];
const ll INF = 2e16+5;
int timer = 0;
void dfs(int u, int p) {
tin[u] = ++timer;
for(auto[v, w] : adj[u]) {
if(v == p) continue;
dfs(v, u);
}
tout[u] = ++timer;
}
bool is_anc(int u, int v1, int v2) {
return (
(tin[v1] <= tin[u] && tout[v1] >= tout[u]) &&
(tin[v2] <= tin[u] && tout[v2] >= tout[u])
);
}
int main() {
cin.tie(0)->sync_with_stdio(0);
int N, S, Q, E; cin >> N >> S >> Q >> E; // rooted at E
for(int i = 0, u, v, w; i < N - 1; ++i) {
cin >> u >> v >> w;
roads.push_back({u, v});
adj[u].push_back({v, w});
adj[v].push_back({u, w});
}
for(int i = 1; i <= N; ++i) dist[i][0] = dist[i][1] = INF;
priority_queue<tuple<ll, int, int>, vector<tuple<ll, int, int>>, greater<>> q;
for(int i = 0, c; i < S; ++i) {
cin >> c;
q.push({0LL, c, c});
dist[c][0] = dist[c][1] = 0;
shop_node[c][0] = shop_node[c][1] = c;
}
while(!q.empty()) {
auto[cur_dist, u, p] = q.top(); q.pop();
if(dist[u][1] < cur_dist) continue;
for (auto [v, w] : adj[u]) {
ll new_dist = cur_dist + w;
if (new_dist < dist[v][0]) {
dist[v][0] = new_dist;
shop_node[v][0] = p;
q.push({dist[v][0], v, p});
} else if (new_dist < dist[v][1] && shop_node[v][0] != p) {
dist[v][1] = new_dist;
shop_node[v][1] = p;
q.push({dist[v][1], v, p});
}
}
}
dfs(E, 0);
for(int i = 0, I, R; i < Q; ++i) {
cin >> I >> R;
--I;
int v1 = roads[I].v1, v2 = roads[I].v2;
if(tin[v2] > tin[v1]) swap(v1, v2);
if(!is_anc(R, v1, v2)) cout << "escaped\n";
else {
int shop1 = shop_node[R][0];
int shop2 = shop_node[R][1];
if(is_anc(shop1, v1, v2)) {
cout << dist[R][0] << "\n";
}
else if(is_anc(shop2, v1, v2)) {
cout << dist[R][1] << "\n";
}
else cout << "oo\n";
}
}
}
