#include <bits/stdc++.h>
using namespace std;
#define ll long long int
#define pb push_back
#define mp make_pair
#define pii pair<int, int>
#define all(x) x.begin(), x.end()
#define u_map unordered_map
#define int ll
const int maxn = 1e5 + 5, mod = 1e9 + 7, inf = 1e15;
vector<pii> adj[maxn], ed;
bool sh[maxn], mark[maxn], is, si;
pii ban;
int n, s, q, e, ans, st[maxn], fn[maxn], cnt, h[maxn];
void dfs1(int v, int par) {
mark[v] = 1;
h[v] = h[par] + 1;
st[v] = cnt;
cnt++;
for (pii x: adj[v]) {
int u = x.second;
if (!mark[u]) {
dfs1(u, v);
}
}
fn[v] = cnt;
cnt++;
}
void dfs(int v, int par) {
mark[v] = 1;
if (v == e) {
is = true;
}
if (sh[v]) {
si = true;
ans = min(ans, par);
}
for (pii u: adj[v]) {
if (!mark[u.second] and !(((ban.first == u.second and ban.second == v) or (ban.first == v and ban.second == u.second)))) {
dfs(u.second, par + u.first);
}
}
}
inline void _clear() {
memset(mark, 0, sizeof mark);
is = false;
si = false;
ans = inf;
}
bool isin(int x, int y) {
if (st[x] <= st[y] and fn[x] >= fn[y]) {
return true;
}
return false;
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
cin >> n >> s >> q >> e;
for (int i = 1; i < n; i++) {
int u, v, w;
cin >> u >> v >> w;
adj[u].pb({w, v});
adj[v].pb({w, u});
ed.pb({u, v});
}
for (int i = 1; i <= s; i++) {
int x;
cin >> x;
sh[x] = 1;
}
if (s == n) {
h[0] = -1;
dfs1(e, 0);
}
while (q--) {
_clear();
int l, r;
cin >> l >> r;
ban = {ed[l - 1].first, ed[l - 1].second};
if (s == n) {
int x = ban.first, y = ban.second;
if (h[y] > h[x]) {
swap(x, y);
}
if (isin(x, r)) {
cout << "0\n";
} else {
cout << "escaped\n";
}
continue;
}
dfs(r, 0);
if (is) {
cout << "escaped\n";
} else {
if (!si) {
cout << "oo\n";
} else {
cout << ans << '\n';
}
}
}
return 0;
}
