#include "bits/stdc++.h"
using namespace std;
const int MAXN = 100'001, MS = 18;
const long long INF = 1e18;
int n, s, q, e;
vector<pair<int, long long>> adj[MAXN];
vector<pair<int, int>> edge;
bool shop[MAXN];
int h[MAXN];
long long dist[MAXN];
long long mn[MS][MAXN];
int jmp[MS][MAXN];
void dfs(int u, int p, int ht) {
if (shop[u]) mn[0][u] = 0;
for (auto v : adj[u]) {
if (v.first == p) continue;
dist[v.first] = dist[u] + v.second;
h[v.first] = ht + 1;
jmp[0][v.first] = u;
dfs(v.first, u, ht + 1);
mn[0][u] = min(mn[0][u], mn[0][v.first] + v.second);
}
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n >> s >> q >> e;
for (int i = 0; i < n - 1; i++) {
int a, b;
long long w;
cin >> a >> b >> w;
edge.push_back({a, b});
adj[a].push_back({b, w});
adj[b].push_back({a, w});
}
for (int i = 0; i < s; i++) {
int a;
cin >> a;
shop[a] = true;
}
for (int i = 1; i <= n; i++) mn[0][i] = INF;
mn[0][e] = 0;
dfs(e, 0, 0);
for (int i = 1; i <= n; i++) {
if (mn[0][i] != INF)
mn[0][i] -= dist[i];
}
for (int i = 1; i < MS; i++) {
for (int j = 1; j <= n; j++) {
jmp[i][j] = jmp[i - 1][jmp[i - 1][j]];
mn[i][j] = min(mn[i - 1][j], mn[i - 1][jmp[i - 1][j]]);
}
}
auto sameSubtree = [&](int a, int b) {
int diff = h[a] - h[b];
for (int i = MS - 1; i >= 0; i--)
if (diff & (1 << i))
a = jmp[i][a];
return a == b;
};
while (q--) {
int a, v;
cin >> a >> v;
a--;
int u = edge[a].first;
if (h[u] < h[edge[a].second]) u = edge[a].second;
if (h[u] <= h[v] && sameSubtree(v, u)) {
long long initDist = dist[v];
long long ans = INF;
int diff = h[v] - h[u];
for (int i = MS - 1; i >= 0; i--) {
if (diff & (1 << i)) {
ans = min(ans, mn[i][v]);
v = jmp[i][v];
}
}
ans = min(ans, mn[0][u]);
if (ans == INF) {
cout << "oo\n";
} else {
cout << initDist + ans << '\n';
}
} else {
cout << "escaped\n";
}
}
}
