// Source: https://usaco.guide/general/io
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll cap = 1e2+1;
vector<pair<ll,ll>> adj[cap];
void dijkstra(){
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
ll n, s, q, e;
cin >> n >> s >> q >> e;
vector<tuple<ll,ll,ll>> edges;
for (ll i{}; i < n-1; i++){
ll a, b, w; cin >> a >> b >> w;
adj[a].push_back({b,w});
adj[b].push_back({a,w});
edges.push_back({a,b,w});
}
vector<ll> shops;
for (ll i{}; i < s; i++){
ll c; cin >> c;
shops.push_back(c);
}
for (ll i{}; i < q; i++){
ll I, r; cin >> I >> r;
ll a, b, w; tie(a, b, w) = edges[I-1];
erase(adj[a], make_pair(b, w));
erase(adj[b], make_pair(a, w));
priority_queue<pair<ll,ll>> pq;
vector<bool> visited(n+1, false);
vector<ll> dist(n+1, 1e18);
dist[r] = 0;
pq.push({0, r});
while (!pq.empty()){
auto t = pq.top(); pq.pop();
ll d = -t.first;
ll v = t.second;
if (visited[v]) continue;
visited[v] = true;
for (auto pr : adj[v]){
ll u = pr.first;
ll wt = pr.second;
if (dist[u] > d + wt){
dist[u] = d + wt;
pq.push({-dist[u], u});
}
}
}
if (dist[e] == 1e18) {
ll ans = 1e18;
for (ll v : shops) {
ans = min(ans, dist[v]);
}
if (ans == 1e18) {
cout << "oo\n";
} else {
cout << ans << "\n";
}
} else {
cout << "escaped\n";
}
adj[a].push_back({b,w});
adj[b].push_back({a,w});
}
}
