#include <bits/stdc++.h>
using namespace std;
#define all(v) v.begin(), v.end()
#define endl '\n'
#define pl(var) " [" << #var << ": " << (var) << "] "
#define ll long long
template<typename A, typename B> ostream& operator<<(ostream &cout, pair<A, B> const &p) { return cout << "[" << p.first << ", " << p.second << "]"; }
template<typename A> ostream& operator<<(ostream &cout, vector<A> const &v) { cout << "["; for(int i = 0; i < (int)v.size(); i++) {if (i) cout << ", "; cout << v[i];} return cout << "]";}
template<typename A, typename B> istream& operator>>(istream& cin, pair<A, B> &p) { cin >> p.first; return cin >> p.second; }
vector<vector<pair<int, int>>> adj;
vector<int> tin, tout, par, dep;
vector<ll int> dist, dp1, dp2;
vector<bool> shop;
int timer = 0;
void dfs(int u, int p, ll int dis, int d = 0) {
dist[u] = dis;
tin[u] = timer++;
par[u] = p;
dep[u] = d;
for (auto [v, w] : adj[u]) {
if (v == p) continue;
dfs(v, u, dis + w, d + 1);
}
if (shop[u]) dp1[u] = dist[u];
else dp1[u] = 1e18;
for (auto [v, wt] : adj[u]) {
if (v == p) continue;
dp1[u] = min(dp1[u], dp1[v]);
}
tout[u] = timer - 1;
}
bool is_acc(int acc, int child) {
if (acc == child) return 1;
return tin[acc] < tin[child] && tin[child] <= tout[acc];
}
void solve() {
int n, s, q, e; cin >> n >> s >> q >> e;
adj.resize(n);
dp1.resize(n);
dp2.resize(n);
tin.resize(n);
tout.resize(n);
dist.resize(n);
shop.resize(n);
par.resize(n);
dep.resize(n);
fill(all(dp1), 1e18);
vector<pair<pair<int, int>, int>> edges;
for (int i = 0; i < n - 1; i++) {
int a, b; cin >> a >> b;
int c; cin >> c;
a--, b--;
adj[a].emplace_back(b, c);
adj[b].emplace_back(a, c);
edges.emplace_back(make_pair(a, b), c);
}
for (int i = 0; i < s; i++) {
int a; cin >> a;
shop[a - 1] = 1;
}
// e is the root
dfs(e - 1, e - 1, 0);
for (int i = 0; i < n; i++) {
dp1[i] = dp1[i] - 2 * dist[i];
}
// eureka!! binary lifting for path queries
const int LOG = 20;
vector<vector<ll int>> jumpNode(n, vector<ll int>(20)), jumpDP(n, vector<ll int>(20));
for (int i = 0; i < n; i++) {
jumpNode[i][0] = par[i];
jumpDP[i][0] = dp1[i];
}
for (int i = 1; i < LOG; i++) {
for (int j = 0; j < n; j++) {
jumpNode[j][i] = jumpNode[jumpNode[j][i - 1]][i - 1];
jumpDP[j][i] = min(jumpDP[j][i - 1], jumpDP[jumpNode[j][i - 1]][i - 1]); // somewhat like sparse tables
}
}
// cout << jumpDP << endl;
auto query = [&](int u, int k) -> ll int {
int pow = LOG;
ll int res = 1e18;
// cout << pl(k) << pl(u) << endl;
// cout << pl(jumpDP[u][0]) << endl;
while (k > 0) {
while (k < (1 << pow)) pow--;
res = min(res, jumpDP[u][pow]);
// cout << pl(jumpDP[u][pow]) << endl;
u = jumpNode[u][pow];
k -= (1 << pow);
}
return res;
};
while (q--) {
int a, b; cin >> a >> b;
a--, b--;
pair<int, int> edge = edges[a].first;
if (is_acc(edge.first, b) && is_acc(edge.second, b)) {
int one = edge.first;
if (dist[one] < dist[edge.second]) {
one = edge.second;
}
ll int res = query(b, dep[b] - dep[one] + 1);
// res = min(res, dp1[b]) << endl;
// cout << pl(dep[one]) << pl(dep[b]) << endl;
if (res >= 1e16) {
cout << "oo" << endl;
} else {
cout << res + dist[b] << endl;
}
} else {
cout << "escaped" << endl;
}
}
}
int main() {
// freopen(".in", "r", stdin);
// freopen(".out", "w", stdout);
ios::sync_with_stdio(false);
cin.tie(nullptr);
int T = 1;
// cin >> T;
while (T--)
solve();
}
