#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ll long long
#define lint long long int
#define debugi(i, f) cerr << "i = " << i << " : f[i] = " << f[i] << "\n";
#define debugii(i, j, f) cerr << "i = " << i << " and j = " << j << " : f[i][j] = " << f[i][j] << "\n";
#define debugiii(i, j, k, f) cerr << "i = " << i << " and j = " << j << " and k = " << k << " : f[i][j][k] = " << f[i][j][k] << "\n";
#define vc vector
#define pr pair
#define ii pair<int, int>
#define iii pair<int, ii>
#define fi first
#define se second
#define Pi 3.1415926535897932384
#define FOR(i, a, b) for (int i = (a); i <= (b); i++)
#define FORD(i, a, b) for (int i = (a); i >= (b); i--)
const ll mod = 1e9 + 7;
const int MOD = 2e9 + 33;
const int N = 1e5 + 2;
int n, s, q, e;
vc<ii> adj[N];
ii edges[N];
bool mark[N];
namespace biLifting {
int h[N], anc[N][19], dist[N], jumpMg[N][19], mg[N];
void dfs (int node, int prenode) {
if (mark[node] == true) mg[node] = dist[node];
else mg[node] = 1e18;
for (ii x : adj[node]) if (x.fi != prenode) {
h[x.fi] = h[node] + 1;
dist[x.fi] = dist[node] + x.se;
anc[x.fi][0] = node;
dfs(x.fi, node);
mg[node] = min(mg[node], mg[x.fi]);
}
}
void computeMg () {
for (int i = 1; i <= n; i++) if (mg[i] != 1e18) {
mg[i] -= 2 * dist[i];
}
}
void preCal () {
jumpMg[e][0] = mg[e];
for (int i = 1; i <= n; i++) if (i != e) {
jumpMg[i][0] = min(mg[i], mg[anc[i][0]]);
}
for (int j = 1; (1 << j) <= n; j++) {
for (int i = 1; i <= n; i++) {
anc[i][j] = anc[anc[i][j - 1]][j - 1];
jumpMg[i][j] = min(jumpMg[i][j - 1], jumpMg[anc[i][j - 1]][j - 1]);
}
}
}
int lca (int u, int v) {
if (h[u] < h[v]) swap(u, v);
int diff = h[u] - h[v];
for (int mask = 0; (1 << mask) <= diff; mask++) {
if (diff & (1 << mask)) {
u = anc[u][mask];
}
}
if (u == v) return u;
int lg = log2(h[u]);
for (int mask = lg; mask >= 0; mask--) {
if (anc[u][mask] != anc[v][mask]) {
u = anc[u][mask];
v = anc[v][mask];
}
}
return anc[u][0];
}
int nearestShop (int root, int u) {
int diff = h[u] - h[root];
// cout << "diff = " << diff << '\n';
// cout << "jumpMg[root][0] = " << jumpMg[root][0] << '\n';
int minMg = mg[u];
for (int mask = 0, cur = u; (1 << mask) <= diff; mask++) {
if ((1 << mask) <= diff) {
// debugii(cur, mask, jumpMg);
minMg = min(minMg, jumpMg[cur][mask]);
cur = anc[cur][mask];
}
}
// cout << "minMg = " << minMg << '\n';
if (minMg == 1e18) return 1e18;
else return dist[u] + minMg;
}
void debug () {
for (int i = 1; i <= n; i++) {
for (int j = 0; (1 << j) <= n; j++) {
debugii(i, j, jumpMg);
}
}
}
}
void runcase (int test) {
cin >> n >> s >> q >> e;
for (int i = 2; i <= n; i++) {
int a, b, w;
cin >> a >> b >> w;
edges[i - 1].fi = a, edges[i - 1].se = b;
adj[a].push_back(ii(b, w));
adj[b].push_back(ii(a, w));
}
for (int i = 1; i <= s; i++) {
int si;
cin >> si;
mark[si] = true;
}
biLifting::dfs(e, 0), biLifting::computeMg(), biLifting::preCal();
// biLifting::debug();
while (q--) {
int I, R;
cin >> I >> R;
int a = edges[I].fi, b = edges[I].se;
if (biLifting::h[a] > biLifting::h[b])
swap(a, b);
int __lca = biLifting::lca(R, b);
// cout << "lca = " << __lca << '\n';
if (biLifting::h[__lca] <= biLifting::h[a]) {
cout << "escaped\n";
continue;
}
int ans = biLifting::nearestShop(b, R);
if (ans == 1e18) cout << "oo\n";
else cout << ans << '\n';
}
}
/**
B1 : kiểm tra lại code templete, code đã học thuộc
đọc kĩ đề
nháp chưa
kiểm tra lại code, đặc biệt là những chỗ đã học thuộc (nhiều khi sai ở đó)
**/
signed main () {
ios_base::sync_with_stdio (false);
cin.tie (0); cout.tie (0);
#ifdef ONLINE_JUDGE
freopen ("runaway.in", "r", stdin);
freopen ("runaway.out", "w", stdout);
#else // online submission
#endif
/// i have a contest soon and i need to learn a much as possible
/// so let become familiar with a bunch of different problems and solution ideas
// stop learning useless algorithm (with you) and solve more problems
//Cứ 7 lần nộp thì chỉ được 1 lần sai
int test = 1;
// cin >> test;
while (test--) runcase(test);
// return 0;
}
