#include <bits/stdc++.h>
template <class T>
using Vec = std::vector<T>;
using ll = long long;
template <class F>
struct RecLambda: private F {
RecLambda(F&& f): F(std::forward<F>(f)) { }
template <class... Args>
decltype(auto) operator () (Args&&... args) const {
return F::operator()(*this, std::forward<Args>(args)...);
}
};
constexpr ll INF = std::numeric_limits<ll>::max() / 2;
int main() {
int N, S, Q, E;
std::cin >> N >> S >> Q >> E;
E -= 1;
Vec<int> A(N - 1), B(N - 1), W(N - 1);
Vec<Vec<std::pair<int, int>>> graph(N);
for (int i = 0; i < N - 1; ++i) {
std::cin >> A[i] >> B[i] >> W[i];
A[i] -= 1;
B[i] -= 1;
graph[A[i]].emplace_back(B[i], W[i]);
graph[B[i]].emplace_back(A[i], W[i]);
}
Vec<bool> shop(N);
while (S--) {
int x;
std::cin >> x;
x -= 1;
shop[x] = true;
}
std::array<Vec<int>, 20> parent;
parent[0] = Vec<int>(N);
Vec<int> in(N), out(N);
Vec<ll> nearest(N, INF), depth(N);
int timer = 0;
RecLambda([&](auto&& dfs, const int u, const int p, const ll d) -> void {
parent[0][u] = p;
in[u] = timer++;
depth[u] = d;
if (shop[u]) {
nearest[u] = 0;
}
for (const auto [v, c]: graph[u]) {
if (v != p) {
dfs(v, u, d + c);
nearest[u] = std::min(nearest[u], nearest[v] + c);
}
}
out[u] = timer;
})(E, E, 0);
std::array<Vec<ll>, 20> min;
min[0] = Vec<ll>(N);
for (int i = 0; i < N; ++i) {
min[0][i] = nearest[i] - depth[i];
}
for (int i = 0; i < 19; ++i) {
parent[i + 1] = Vec<int>(N);
min[i + 1] = Vec<ll>(N);
for (int j = 0; j < N; ++j) {
parent[i + 1][j] = parent[i][parent[i][j]];
min[i + 1][j] = std::min(min[i][j], min[i][parent[i][j]]);
}
}
while (Q--) {
int e, u;
std::cin >> e >> u;
e -= 1;
u -= 1;
const auto p = (depth[A[e]] > depth[B[e]] ? A[e] : B[e]);
if (in[p] <= in[u] and in[u] <= out[p]) {
ll ans = INF;
const auto add = depth[u];
// for (int i = 19; i >= 0; --i) {
// if (depth[parent[i][u]] >= depth[p]) {
// ans = std::min(ans, min[i][u] + add);
// u = parent[i][u];
// }
// }
ans = std::min(ans, min[0][p] + add);
while (u != p) {
ans = std::min(ans, min[0][u] + add);
u = parent[0][u];
}
if (ans == INF) {
std::cout << "oo\n";
}
else {
std::cout << ans << '\n';
}
}
else {
std::cout << "escaped\n";
}
}
return 0;
}
