#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
#define SZ(x) (ll) x.size()
#define F first
#define S second
#define lc id << 1
#define rc lc | 1
const ll N = 1e5 + 10, MOD = 1e9 + 7, INF = 1e18;
int V[N], S[N], L[N], R[N], n, q, k, M, timer; ll A[N], H[N], lazy[N << 2], seg[N << 2];
vector<pair<int, ll>> Q[N], adj[N]; pair<int, int> E[N];
void preDFS(int v, int p = -1) {
L[v] = timer++;
V[L[v]] = v;
for (auto u : adj[v]) {
if (u.F != p) {
H[u.F] = H[v] + u.S;
preDFS(u.F, v);
}
}
R[v] = timer;
}
void build(int id = 1, int l = 0, int r = N) {
if (r - l == 1) {
if (S[V[l]]) seg[id] = H[V[l]];
else seg[id] = INF;
return;
}
int mid = (l + r) >> 1;
build(lc, l, mid);
build(rc, mid, r);
seg[id] = min(seg[lc], seg[rc]);
}
void shift(int id, int l, int r) {
seg[id] += lazy[id];
if (r - l > 1) {
lazy[lc] += lazy[id];
lazy[rc] += lazy[id];
}
lazy[id] = 0;
}
void update(int ql, int qr, ll x, int id = 1, int l = 0, int r = N) {
shift(id, l, r);
if (qr <= l || r <= ql) return;
if (ql <= l && r <= qr) {
lazy[id] += x;
return shift(id, l, r);
}
int mid = (l + r) >> 1;
update(ql, qr, x, lc, l, mid);
update(ql, qr, x, rc, mid, r);
seg[id] = min(seg[lc], seg[rc]);
}
ll get(int ql, int qr, int id = 1, int l = 0, int r = N) {
shift(id, l, r);
if (qr <= l || r <= ql) return INF;
if (ql <= l && r <= qr) return seg[id];
int mid = (l + r) >> 1;
return min(get(ql, qr, lc, l, mid), get(ql, qr, rc, mid, r));
}
int ispar(int v, int u) {
return L[v] <= L[u] && R[u] <= R[v];
}
void DFS(int v, int p = -1) {
for (auto u : Q[v]) {
int eu = E[u.F].F, ev = E[u.F].S;
if (H[eu] < H[ev]) swap(eu, ev);
if (ispar(eu, v) == ispar(eu, M)) A[u.S] = -1;
else {
if (ispar(eu, v)) A[u.S] = get(L[eu], R[eu]);
else A[u.S] = min(get(L[1], L[eu]), get(R[eu], R[1]));
}
}
for (auto u : adj[v]) {
if (u.F == p) continue;
update(L[1], R[1], u.S);
update(L[u.F], R[u.F], -2 * u.S);
DFS(u.F, v);
update(L[1], R[1], -u.S);
update(L[u.F], R[u.F], 2 * u.S);
}
}
int main() {
scanf("%d%d%d%d", &n, &k, &q, &M);
for (int i = 1; i < n; i++) {
int u, v; ll w; scanf("%d%d%lld", &u, &v, &w);
adj[u].push_back({v, w});
adj[v].push_back({u, w});
E[i].F = u, E[i].S = v;
}
for (int i = 1; i <= k; i++) {
int v; scanf("%d", &v);
S[v] = 1;
}
preDFS(1);
build();
for (int i = 1; i <= q; i++) {
int v, l; scanf("%d%d", &l, &v);
Q[v].push_back({l, i});
}
DFS(1);
for (int i = 1; i <= q; i++) {
if (A[i] == -1) printf("escaped\n");
else if (A[i] <= (ll) 1e15) printf("%lld\n", A[i]);
else printf("oo\n");
}
return 0;
}
