#include <bits/stdc++.h>
using namespace std;
#define ar array
#define all(v) begin(v), end(v)
#define sz(v) int(std::size(v))
using i64 = long long;
using pii = pair<int, int>;
using vi = vector<int>;
const i64 INF = 1e18;
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int N, S, Q, E;
cin >> N >> S >> Q >> E, E--;
vector<vector<pii>> adj(N);
vector<pii> edges(N - 1);
for (auto &[i, j] : edges) {
int w; cin >> i >> j >> w, i--, j--;
adj[i].push_back({j, w}), adj[j].push_back({i, w});
}
vi is_shop(N);
while (S--) {
int i; cin >> i, i--;
is_shop[i] = 1;
}
const int LOG = 17;
vector<ar<int, LOG>> parent(N);
vector<ar<i64, LOG>> min_v(N);
vi tin(N), tout(N), depth(N);
vector<i64> dist_root(N);
int timer = 0;
vector<i64> dist(N);
auto dfs = [&](auto dfs, int p, int i) -> void {
dist[i] = is_shop[i] ? 0 : INF;
tin[i] = timer++;
parent[i][0] = p;
for (int l = 1; l < LOG; l++) parent[i][l] = parent[parent[i][l - 1]][l - 1];
for (auto [j, w] : adj[i]) if (p != j) {
depth[j] = depth[i] + 1;
dist_root[j] = dist_root[i] + w;
dfs(dfs, i, j);
dist[i] = min(dist[i], dist[j] + w);
}
tout[i] = timer - 1;
};
dfs(dfs, E, E);
auto make_v = [&](auto make_v, int i) -> void {
min_v[i][0] = dist[i] - dist_root[i];
for (int l = 1; l < LOG; l++) min_v[i][l] = min(min_v[i][l - 1], min_v[parent[i][l - 1]][l - 1]);
for (auto [j, w] : adj[i]) if (parent[i][0] != j) make_v(make_v, j);
};
make_v(make_v, E);
vi lower(N - 1);
for (int i = 0; i < sz(edges); i++)
lower[i] = tin[edges[i].first] < tin[edges[i].second] ? edges[i].second : edges[i].first;
auto is_anc = [&](int i, int j) {
return tin[i] <= tin[j] && tout[i] >= tout[j];
};
while (Q--) {
int h, i; cin >> h >> i, h--, i--;
int j = lower[h];
if (!is_anc(j, i)) {
cout << "escaped\n";
continue;
}
int d = depth[i] - depth[j] + 1, v = i;
i64 best = INF;
for (int l = 0; l < LOG; l++) if (d >> l & 1) {
best = min(best, min_v[v][l]);
v = parent[v][l];
}
best += dist_root[i];
if (best > INF / 2) {
cout << "oo\n";
continue;
}
cout << best << '\n';
}
}
