#include <bits/stdc++.h>
using namespace std;
using lint = long long;
const lint INF = 1e18;
const int LOG = 18;
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int N, S, Q, E;
cin >> N >> S >> Q >> E;
E--;
vector<pair<int, int>> edges;
vector<vector<pair<int, int>>> adj(N);
for (int i = 1; i < N; i++) {
int u, v, w;
cin >> u >> v >> w;
u--, v--;
edges.emplace_back(u, v);
adj[u].emplace_back(v, w);
adj[v].emplace_back(u, w);
}
vector<int> depth(N);
vector<lint> dp(N, INF);
vector<lint> dist(N, 0);
vector<vector<int>> par(LOG, vector<int>(N, -1));
vector<vector<lint>> lift(LOG, vector<lint>(N, INF));
for (int i = 0; i < S; i++) {
int x;
cin >> x;
dp[--x] = 0;
}
const auto Dfs = [&](const auto &self, int u, int p) -> void {
par[0][u] = p;
vector<pair<lint, int>> ls;
ls.emplace_back(dp[u], u);
for (auto [v, w] : adj[u]) if (v != p) {
dist[v] = dist[u] + w;
depth[v] = depth[u] + 1;
self(self, v, u);
ls.emplace_back(dp[v] + w, v);
dp[u] = min(dp[u], dp[v] + w);
}
sort(begin(ls), end(ls));
for (auto [v, w] : adj[u]) if (v != p) {
lift[0][v] = (ls[0].second == v ? ls[1].first : ls[0].first) - dist[u];
}
};
Dfs(Dfs, E, -1);
for (int j = 1; j < LOG; j++) {
for (int u = 0; u < N; u++) {
par[j][u] = par[j - 1][u];
lift[j][u] = lift[j - 1][u];
if (par[j - 1][u] != -1) {
par[j][u] = par[j - 1][par[j - 1][u]];
lift[j][u] = min(lift[j][u], lift[j - 1][par[j - 1][u]]);
}
}
}
const auto IsAncestor = [&](int x, int y) -> bool { // is x ancestor of y?
if (depth[x] > depth[y]) return false;
int d = depth[y] - depth[x];
for (int i = 0; i < LOG; i++) {
if ((d >> i) & 1) {
y = par[i][y];
}
}
return x == y;
};
const auto GetMinCost = [&](int u, int d) -> lint {
if (d < 0) return INF;
lint ans = INF;
for (int i = 0; i < LOG; i++) {
if ((d >> i) & 1) {
ans = min(ans, lift[i][u]);
u = par[i][u];
}
}
ans = min(ans, lift[0][u]);
return ans;
};
while (Q--) {
int i, r;
cin >> i >> r;
i--, r--;
if (IsAncestor(edges[i].first, r) && IsAncestor(edges[i].second, r)) {
int d = depth[r] - max(depth[edges[i].first], depth[edges[i].second]);
lint ans = min(dp[r], dist[r] + GetMinCost(r, d - 1));
if (ans > (INF / 100)) {
cout << "oo\n";
} else {
cout << ans << '\n';
}
} else {
cout << "escaped\n";
}
}
return 0;
}
