#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 100100;
const int K = 20;
const ll INF = 1e18;
int n, s, q, e;
int a[N], b[N];
vector<pair<ll, int>> g[N];
int c[N];
bool good[N];
int tin[N], tout[N], tt;
ll h[N];
ll d[N];
int up[K][N];
ll mn[K][N];
ll val[N];
bool anc(int v, int u) {
return tin[v] <= tin[u] && tout[v] >= tout[u];
}
void dfs(int v) {
tin[v] = tt++;
d[v] = INF;
for (auto [w, u] : g[v]) {
if (u != up[0][v]) {
up[0][u] = v;
h[u] = h[v] + w;
dfs(u);
d[v] = min(d[v], d[u] + w);
}
}
if (good[v]) {
d[v] = 0;
}
val[v] = d[v] - h[v];
tout[v] = tt;
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cin >> n >> s >> q >> e;
--e;
for (int i = 0; i < n - 1; ++i) {
ll w;
cin >> a[i] >> b[i] >> w;
--a[i];
--b[i];
g[a[i]].emplace_back(w, b[i]);
g[b[i]].emplace_back(w, a[i]);
}
for (int i = 0; i < s; ++i) {
cin >> c[i];
--c[i];
good[c[i]] = true;
}
up[0][e] = e;
dfs(e);
for (int i = 0; i < n - 1; ++i) {
if (tin[a[i]] > tin[b[i]]) {
swap(a[i], b[i]);
}
}
for (int v = 0; v < n; ++v) {
mn[0][v] = val[up[0][v]];
}
for (int i = 1; i < K; ++i) {
for (int v = 0; v < n; ++v) {
up[i][v] = up[i - 1][up[i - 1][v]];
mn[i][v] = min(mn[i - 1][v], mn[i - 1][up[i - 1][v]]);
}
}
while (q--) {
int id, v;
cin >> id >> v;
--id;
--v;
if (!anc(b[id], v)) {
cout << "escaped\n";
continue;
}
if (d[b[id]] == INF) {
cout << "oo\n";
continue;
}
int vv = v;
ll ans = val[v];
for (int i = K - 1; i >= 0; --i) {
if (anc(b[id], up[i][v])) {
ans = min(ans, mn[i][v]);
v = up[i][v];
}
}
ans += h[vv];
cout << ans << "\n";
}
return 0;
}
