#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
#include "debug.h"
#else
#define dbg(...) 47
#endif
#define int long long
constexpr int N = 1e5;
constexpr int inf = 1e18;
vector<pair<int, int>> g[N];
int par[N], lvl[N], tin[N], tout[N], up[N];
int timer = 0;
void init(int u, int p) {
tin[u] = timer++;
for (auto [v, w] : g[u]) {
if (v != p) {
up[v] = w;
par[v] = u;
lvl[v] = lvl[u] + 1;
init(v, u);
}
}
tout[u] = timer - 1;
}
bool is[N];
int dp[N], sum[N];
void dfs(int u, int p) {
if (is[u]) {
dp[u] = 0;
}
for (auto [v, w] : g[u]) {
if (v != p) {
sum[v] = sum[u] + w;
dfs(v, u);
dp[u] = min(dp[u], dp[v] + w);
}
}
}
struct HLD {
int n, timer;
vector<vector<int>> g;
vector<int> sz, heavy, par, in, head;
struct SegmentTree {
int n;
vector<int> t;
void init(int _n) {
n = _n;
t.assign(4 * n, inf);
}
int merge(int x, int y) {
return min(x, y);
}
void update(int id, int tl, int tr, int i, int v) {
if (tl == tr) {
t[id] = v;
return;
}
int x = (id << 1) + 1, y = x + 1, tm = (tl + tr) >> 1;
if (i <= tm) {
update(x, tl, tm, i, v);
} else {
update(y, tm + 1, tr, i, v);
}
t[id] = merge(t[x], t[y]);
}
int get(int id, int tl, int tr, int l, int r) {
if (r < tl || tr < l) return inf;
if (l <= tl && tr <= r) return t[id];
int x = (id << 1) + 1, y = x + 1, tm = (tl + tr) >> 1;
return merge(get(x, tl, tm, l, r), get(y, tm + 1, tr, l, r));
}
void update(int i, int v) { update(0, 0, n - 1, i, v); }
int get(int l, int r) { return get(0, 0, n - 1, l, r); }
} t;
HLD (int _n, vector<vector<int>> &_g) { init(_n, _g); }
void init(int _n, vector<vector<int>> &_g) {
n = _n;
g = _g;
sz.assign(n, 0);
heavy.assign(n, -1);
par.assign(n, -1);
in.assign(n, 0);
head.assign(n, 0);
timer = 0;
dfs(0, -1);
hld(0, 0);
t.init(n);
}
void dfs(int u, int p) {
sz[u] = 1;
par[u] = p;
int mx = 0;
for (auto v : g[u]) {
if (v == p) continue;
dfs(v, u);
sz[u] += sz[v];
if (sz[v] > mx) {
mx = sz[v];
heavy[u] = v;
}
}
}
void hld(int u, int h) {
in[u] = timer++;
head[u] = h;
if (heavy[u] != -1) {
hld(heavy[u], h);
}
for (auto v : g[u]) {
if (v == par[u] || v == heavy[u]) continue;
hld(v, v);
}
}
int get(int x, int y) {
int ret = inf;
while (head[x] != head[y]) {
if (in[head[x]] < in[head[y]]) swap(x, y);
ret = t.merge(ret, t.get(in[head[x]], in[x]));
x = par[head[x]];
}
if (in[x] < in[y]) swap(x, y);
ret = t.merge(ret, t.get(in[y], in[x]));
return ret;
}
void update(int u, int x) {
t.update(in[u], x);
}
};
signed main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n, k, q, e;
cin >> n >> k >> q >> e;
vector<int> a(n - 1), b(n - 1), w(n - 1);
vector<vector<int>> adj(n);
for (int i = 0; i < n - 1; i++) {
cin >> a[i] >> b[i] >> w[i];
a[i]--; b[i]--;
g[a[i]].push_back({b[i], w[i]});
g[b[i]].push_back({a[i], w[i]});
adj[a[i]].push_back(b[i]);
adj[b[i]].push_back(a[i]);
}
for (int i = 0; i < n; i++) {
dp[i] = inf;
}
for (int i = 0; i < k; i++) {
int s;
cin >> s;
s--;
is[s] = true;
}
e--;
init(e, -1);
dfs(e, -1);
HLD h(n, adj);
for (int i = 0; i < n; i++) {
h.update(i, dp[i] - sum[i]);
}
while (q--) {
int i, r;
cin >> i >> r;
i--; r--;
int u = a[i], v = b[i];
if (lvl[u] > lvl[v]) {
swap(u, v);
}
if (tin[v] <= tin[r] && tin[r] <= tout[v]) {
int res = h.get(r, v) + sum[r];
if (res >= inf / 2) {
cout << "oo\n";
} else {
cout << res << '\n';
}
} else {
cout << "escaped\n";
}
}
return 0;
}
