#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define int long long
const int MOD = 1e9 + 7;
const int INF = 1e15;
const int N = 1e6;
int n, m, k, a, b, c, d, h, l, r, q, u, v, x, y;
int s, e;
vector<int> arr(N);
vector<set<int>> adj(N);
vector<bool> vis(N);
map<pair<int, int>, int> weight;
set<int> shops;
bool found = 0;
void dfs(int node, int d) {
if(found) return;
vis[node] = 1;
// cout << node << " ";
if(node==e) {
// cout << node << " ";
found = true;
return;
}
if(shops.find(node) != shops.end()) {
c = min(c, d);
// cout << c << " ";
}
for(auto j : adj[node]) {
if(!vis[j]) {
dfs(j, d+weight[{node, j}]);
}
}
}
void solve() {
cin >> n >> s >> q >> e;
vector<pair<int, int>> edges(n+1);
for(int i = 1; i<n; i++) {
cin >> a >> b >> c;
adj[a].insert(b);
adj[b].insert(a);
weight[{a, b}] = c;
weight[{b, a}] = c;
edges[i] = {a, b};
}
for(int i = 0; i<s; i++) {
cin >> a;
shops.insert(a);
}
while(q--) {
cin >> l >> r;
adj[edges[l].first].erase(edges[l].second);
adj[edges[l].second].erase(edges[l].first);
c = INF;
found = 0;
dfs(r, 0);
if(found) cout << "escaped";
else if(c == INF) {
cout << "oo";
}
else {
cout << c;
}
cout << "\n";
adj[edges[l].first].insert(edges[l].second);
adj[edges[l].second].insert(edges[l].first);
for(int i = 1; i<=n; i++) vis[i] = 0;
}
}
int32_t main() {
ios::sync_with_stdio(false);
cout.tie(0); cin.tie(0);
int tc = 1;
// cin >> tc;
while(tc--) {
solve();
cout << "\n";
}
return 0;
}
