#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ari2 = array<int, 2>;
#define vt vector
#define size(x) (int((x).size()))
#define all(x) begin(x), end(x)
#define REP(a, b, c, d) for (int a = (b); (d) > 0 ? a <= (c) : a >= (c); a += (d))
#define FOR(a, b, c) REP(a, b, c, 1)
#define ROF(a, b, c) REP(a, b, c, -1)
#define chmax(a, b) a = a > (b) ? a : (b)
#define chmin(a, b) a = a < (b) ? a : (b)
constexpr int mxN = 100000;
constexpr ll INF = 0x3f3f3f3f3f3f3f3f;
int N, S, Q, E, edges[mxN][2];
vt<ari2> adj[mxN];
int tin[mxN], tout[mxN], timer, lift[mxN][17];
ll depth[mxN];
bool shop[mxN];
void dfs(int i, int p) {
tin[i] = timer++;
for (auto [j, v] : adj[i]) {
if (j == p)
continue;
depth[j] = depth[i] + v;
dfs(j, i);
}
tout[i] = timer - 1;
lift[i][0] = p;
}
bool ia(int a, int b) {
return tin[a] <= tin[b] && tin[b] <= tout[a];
}
int LCA(int a, int b) {
if (ia(a, b))
return a;
if (ia(b, a))
return b;
ROF(i, 16, 0)
a = ia(lift[a][i], b) ? a : lift[a][i];
return lift[a][0];
}
ll dist(int a, int b) {
return depth[a] + depth[b] - 2 * depth[LCA(a, b)];
}
int szs[mxN];
bool dead[mxN];
int gs(int i, int p) {
szs[i] = 1;
for (auto [j, _] : adj[i])
if (!dead[j] && j != p)
szs[i] += gs(j, i);
return szs[i];
}
int fc(int i, int n) {
int p = i;
bool flag = true;
while (flag) {
flag = false;
for (auto [j, _] : adj[i])
if (!dead[j] && j != p && szs[j] > n >> 1) {
p = i;
i = j;
flag = true;
break;
}
}
return i;
}
int pr[mxN];
void cd_init(int i, int p) {
int c = fc(i, gs(i, i));
pr[c] = p;
dead[c] = true;
for (auto [j, _] : adj[c])
if (!dead[j])
cd_init(j, c);
}
struct Node {
ll val = INF;
Node *lft = nullptr, *rht = nullptr;
void upd(int p, ll v, int tl, int tr) {
if (tl == tr)
chmin(val, v);
else {
int tm = tl + tr >> 1;
if (p > tm) {
if (!rht)
rht = new Node;
rht->upd(p, v, tm+1, tr);
} else {
if (!lft)
lft = new Node;
lft->upd(p, v, tl, tm);
}
val = min(lft ? lft->val : INF, rht ? rht->val : INF);
}
}
ll qry(int ql, int qr, int tl, int tr) {
if (tl > qr || tr < ql)
return INF;
if (ql <= tl && tr <= qr)
return val;
int tm = tl + tr >> 1;
return min(lft ? lft->qry(ql, qr, tl, tm) : INF, rht ? rht->qry(ql, qr, tm+1, tr) : INF);
}
} sts[mxN];
void init() {
dfs(0, 0);
FOR(j, 1, 16)
FOR(i, 0, N-1)
lift[i][j] = lift[lift[i][j-1]][j-1];
cd_init(0, -1);
FOR(i, 0, N-1)
if (shop[i])
for (int j = i; ~j; j = pr[j])
sts[j].upd(tin[i], dist(i, j), 0, N-1);
}
signed main() {
#ifndef DEBUG
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
#endif
cin >> N >> S >> Q >> E, E--;
FOR(i, 1, N-1) {
int &a = edges[i][0], &b = edges[i][1], c;
cin >> a >> b >> c;
adj[--a].push_back({--b, c});
adj[b].push_back({a, c});
}
FOR(_, 1, S) {
int v;
cin >> v;
shop[--v] = true;
}
init();
while (Q--) {
int x, y;
cin >> x >> y, y--;
int a = edges[x][0], b = edges[x][1];
if (ia(b, a))
swap(a, b);
bool in_sub = ia(b, y);
if (ia(b, E) && in_sub || !ia(b, E) && !in_sub) {
cout << "escaped\n";
continue;
}
ll ans = INF;
for (int j = y; ~j; j = pr[j]) {
if (in_sub ^ ia(b, j))
continue;
ll d = dist(j, y);
if (in_sub)
ans = min(ans, sts[j].qry(tin[b], tout[b], 0, N-1) + dist(j, y));
else
ans = min({ans - d, sts[j].qry(0, tin[b]-1, 0, N-1), sts[j].qry(tout[b]+1, N-1, 0, N-1)}) + d;
}
if (ans < INF)
cout << ans;
else
cout << "oo";
cout << '\n';
}
}
