#include <bits/stdc++.h>
//ako ovaj vaso daso misli da me pobedjuje.....
using namespace std;
#define int long long
#define f first
#define s second
const int N = 1e5 + 69;
const int K = 18;
const int inf = 1e18;
int up[N][K];
int n, s, q, e, cnt[N], dep[N], par[N], sz[N], b[N];
int st[4 * N];
int tin[N], tout[N], timer, vis[N];
vector<int> shop;
vector<pair<int, int>> g[N];
vector<tuple<int, int, int>> edges;
void modify(int v, int tl, int tr, int l, int r, int val) {
if (tl > r || tr < l)
return;
else if (tl >= l && tr <= r) {
if (val == 1)
st[v] = inf;
else {
if (tl == tr)
st[v] = b[tl];
else
st[v] = min(st[v * 2], st[v * 2 + 1]);
}
}
else {
int mid = (tl + tr) / 2;
modify(v * 2, tl, mid, l, r, val);
modify(v * 2 + 1, mid + 1, tr, l, r, val);
st[v] = min(st[v * 2], st[v * 2 + 1]);
}
}
int get(int v, int tl, int tr, int l, int r) {
if (tl > r || tr < l || st[v] == inf)
return inf;
else if (tl >= l && tr <= r)
return st[v];
else {
int mid = (tl + tr) / 2;
return min(get(v * 2, tl, mid, l, r), get(v * 2 + 1, mid + 1, tr, l, r));
}
}
void dfs_sz(int v, int p) {
if (vis[v]) {
sz[v] = 0;
return;
}
sz[v] = 1;
for (auto u : g[v]) {
if (u.f == p)
continue;
dfs_sz(u.f, v);
sz[v] += sz[u.f];
}
}
int find_cent(int v, int p, int x) {
for (auto u : g[v]) {
if (u.f != p && !vis[u.f] && sz[u.f] > x / 2)
return find_cent(u.f, v, x);
}
return v;
}
void build(int v, int p) {
dfs_sz(v, -1);
int c = find_cent(v, -1, sz[v]);
vis[c] = 1;
par[c] = p;
for (auto u : g[c]) {
if (!vis[u.f])
build(u.f, c);
}
}
bool anc(int a, int b) {
return tin[a] <= tin[b] && tout[a] >= tout[b];
}
int Lca(int a, int b) {
if (anc(a, b))
return a;
else if (anc(b, a))
return b;
for (int i = K - 1;i >= 0;i--) {
if (!anc(up[a][i], b) && up[a][i] > 0)
a = up[a][i];
}
return up[a][0];
}
int distance(int a, int b) {
return dep[a] + dep[b] - 2 * dep[Lca(a, b)];
}
void dfs(int v, int p) {
tin[v] = ++timer;
up[v][0] = p;
b[tin[v]] = dep[v];
for (int i = 1;i < K;i++)
up[v][i] = up[up[v][i - 1]][i - 1];
for (auto u : g[v]) {
if (u.f == p)
continue;
dep[u.f] = dep[v] + u.s;
dfs(u.f, v);
}
tout[v] = timer;
}
signed main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int tt = 1;
//cin >> tt;
while (tt--) {
cin >> n >> s >> q >> e;
for (int i = 1;i <= n - 1;i++) {
int a, b, w;
cin >> a >> b >> w;
g[a].push_back({b, w});
g[b].push_back({a, w});
edges.push_back({a, b, w});
}
dfs(1, -1);
build(1, -1);
for (int i = 0;i <= 4 * n;i++)
st[i] = inf;
for (int i = 1;i <= s;i++) {
int x;
cin >> x;
modify(1, 1, n, tin[x], tin[x], 0);
}
for (int j = 0;j < q;j++) {
int i, start;
cin >> i >> start;
--i;
int x, a, b, w;
tie(a, b, w) = edges[i];
x = (dep[a] > dep[b] ? a : b);
int ans = inf;
if (anc(x, e) && anc(x, start))
ans = -1;
else if (!anc(x, e) && !anc(x, start))
ans = -1;
else {
int t = start;
if (!anc(x, start))
modify(1, 1, n, tin[x], tout[x], 1);
while (t != -1) {
if (anc(x, t) == anc(x, start)) {
int y = get(1, 1, n, tin[t], tout[t]);
if (y != inf)
ans = min(ans, y + distance(t, start) - dep[t]);
}
t = par[t];
}
if (!anc(x, start))
modify(1, 1, n, tin[x], tout[x], 0);
}
if (ans == inf)
cout << "oo\n";
else if (ans == -1)
cout << "escaped\n";
else
cout << ans << '\n';
}
}
return 0;
}
