#include <bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define dl double
#define st first
#define nd second
#define II pair <int, int>
using namespace std;
const int N = 5 + 1e5;
const ll inf = 7 + 1e18;
struct Segment {
int n;
vector <ll> tree, a;
Segment (int _n = 0) : n(_n) {
tree.assign(4 * n + 1, 0);
a.assign(4 * n + 1, 0);
}
void pull(int node, ll val) {
tree[node] += val;
a[node] += val;
}
void push(int node) {
if (a[node] != 0) {
pull(2 * node, a[node]);
pull(2 * node + 1, a[node]);
a[node] = 0;
}
}
void update(int l, int r, int node, int u, int v, ll val) {
if (r < u || v < l || v < u)
return;
if (u <= l && r <= v) {
pull(node, val);
return;
}
push(node);
int mid = (l + r) / 2;
update(l, mid, 2 * node, u, v, val);
update(mid + 1, r, 2 * node + 1, u, v, val);
tree[node] = min(tree[2 * node], tree[2 * node + 1]);
}
ll get(int l, int r, int node, int u, int v) {
if (r < u || v < l || v < u)
return inf;
if (u <= l && r <= v)
return tree[node];
push(node);
int mid = (l + r) / 2;
return min(get(l, mid, 2 * node, u, v), get(mid + 1, r, 2 * node + 1, u, v));
}
};
struct Edge {
int u, v;
ll w;
};
int n, m, q, sink, node;
vector <Edge> e;
vector <int> l, r, a;
vector <ll> ans;
vector <vector <int>> adj;
vector <vector <II>> g;
Segment f;
void dfs(int u) {
l[u] = ++ node;
for (int i : adj[u]) {
int v = e[i].u + e[i].v - u;
if (l[v])
continue;
dfs(v);
}
r[u] = node;
}
void dfs_update(int u) {
for (int i : adj[u]) {
int v = e[i].u + e[i].v - u;
if (l[v] < l[u])
continue;
dfs_update(v);
int lo = 1, hi = m;
while (lo < hi) {
int mid = (lo + hi) / 2;
if (l[v] <= l[a[mid]])
hi = mid;
else
lo = mid + 1;
}
if (l[v] <= l[a[lo]] && l[a[lo]] <= r[v]) {
int le = lo;
hi = m;
while (lo < hi) {
int mid = (lo + hi + 1) / 2;
if (l[a[mid]] <= r[v])
lo = mid;
else
hi = mid - 1;
}
f.update(1, m, 1, le, lo, e[i].w);
}
}
}
ll get(int L, int R) {
if (R < L)
return inf;
int lo = 1, hi = m;
while (lo < hi) {
int mid = (lo + hi) / 2;
if (L <= l[a[mid]])
hi = mid;
else
lo = mid + 1;
}
if (l[a[lo]] < L || R < l[a[lo]])
return inf;
int le = lo;
hi = m;
while (lo < hi) {
int mid = (lo + hi + 1) / 2;
if (l[a[mid]] <= R)
lo = mid;
else
hi = mid - 1;
}
return f.get(1, m, 1, le, lo);
}
void dfs_query(int u) {
for (II z : g[u]) {
int i = z.st, id = z.nd, v = e[i].v;
if (l[v] <= l[u] && l[u] <= r[v])
ans[id] = get(l[v], r[v]);
else
ans[id] = min(get(1, l[v] - 1), get(r[v] + 1, n));
}
for (int i : adj[u]) {
int v = e[i].u + e[i].v - u;
if (l[v] < l[u])
continue;
f.update(1, m, 1, 1, m, e[i].w);
int lo = 1, hi = m, L = 0, R = -1;
while (lo < hi) {
int mid = (lo + hi) / 2;
if (l[v] <= l[a[mid]])
hi = mid;
else
lo = mid + 1;
}
if (l[v] <= l[a[lo]] && l[a[lo]] <= r[v]) {
L = lo;
hi = m;
while (lo < hi) {
int mid = (lo + hi + 1) / 2;
if (l[a[mid]] <= r[v])
lo = mid;
else
hi = mid - 1;
}
R = lo;
f.update(1, m, 1, L, R, -e[i].w * 2);
}
dfs_query(v);
f.update(1, m, 1, 1, m, -e[i].w);
f.update(1, m, 1, L, R, e[i].w * 2);
}
}
int check(int u, int v) {
return l[u] <= l[v] && l[v] <= r[u];
}
bool cmp(int u, int v) {
return l[u] < l[v];
}
int main() {
#define TASKNAME ""
ios_base :: sync_with_stdio (0);
cin.tie (0);
if ( fopen( TASKNAME".inp", "r" ) ) {
freopen (TASKNAME".inp", "r", stdin);
freopen (TASKNAME".out", "w", stdout);
}
cin >> n >> m >> q >> sink;
e.resize(n);
adj.resize(n + 1);
for (int i = 1; i < n; i ++) {
cin >> e[i].u >> e[i].v >> e[i].w;
adj[e[i].u].push_back(i);
adj[e[i].v].push_back(i);
}
l.assign(n + 1, 0);
r.assign(n + 1, 0);
dfs(1);
a.assign(m + 1, 0);
for (int i = 1; i <= m; i ++)
cin >> a[i];
sort(a.begin() + 1, a.end(), cmp);
f = Segment(m);
dfs_update(1);
for (int i = 1; i < n; i ++)
if (l[e[i].u] > l[e[i].v])
swap(e[i].u, e[i].v);
g.resize(n + 1);
ans.assign(q + 1, inf);
for (int i = 1; i <= q; i ++) {
int id, u;
cin >> id >> u;
if (check(e[id].v, u) == check(e[id].v, sink))
ans[i] = -1;
else
g[u].push_back({id, i});
}
dfs_query(1);
for (int i = 1; i <= q; i ++)
if (ans[i] < 0)
cout << "escaped\n";
else if (ans[i] < inf)
cout << ans[i] << '\n';
else
cout << "oo\n";
return 0;
}
