#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vi = vector<int>;
#define pb push_back
#define rsz resize
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
using pi = pair<int,int>;
#define f first
#define s second
#define mp make_pair
const int MX = 100005;
const ll INF = (ll) 1e18;
vector<pi> adj[MX]; ll dep[MX], dp[MX]; int tin[MX], tout[MX]; bool village[MX];
template<int SZ> struct LCA{
int depth[SZ]; int p[SZ][33]; vector<int> adj[SZ];
void addEdge(int u, int v){
adj[u].push_back(v); adj[v].push_back(u);
}
void dfs(int v, int par){
for(int to : adj[v]){
if(to != par){
p[to][0] = v; depth[to] = depth[v] + 1;
dfs(to, v);
}
}
}
void precomp(int root) {
for (int i = 0; i < SZ; i++) {
for (int j = 0; j < 32; j++) {
p[i][j] = -1;
}
}
p[root][0] = root;
dfs(root, -1);
for (int j = 1; j < 32; j++) {
for (int i = 0; i < SZ; i++) {
if (p[i][j - 1] == -1) {
p[i][j] = -1;
} else {
p[i][j] = p[p[i][j - 1]][j - 1];
}
}
}
}
int gdep(int v) {
return depth[v];
}
int query(int a, int b) {
if (depth[a] > depth[b]) {
swap(a, b);
}
int lift = depth[b] - depth[a];
for (int j = 31; j >= 0; j--) {
if (lift & (1 << j)) {
b = p[b][j];
}
}
for (int j = 31; j >= 0; j--) {
if (p[a][j] != p[b][j]) {
a = p[a][j];
b = p[b][j];
}
}
return (a == b) ? a : p[a][0];
}
};
template<int SZ> struct BLIFT{
vector<int> adj[SZ]; int p[SZ][33]; ll p_min[SZ][33]; int depth[SZ];
void addEdge(int u, int v){
adj[u].pb(v); adj[v].pb(u);
}
void dfs(int v, int par){
for(int to : adj[v]){
if(to != par){
p[to][0] = v; depth[to] = depth[v] + 1;
dfs(to, v);
}
}
}
void precomp(int root, ll dp[MX]) {
for (int i = 0; i < SZ; i++) {
for (int j = 0; j < 32; j++) {
p[i][j] = -1;
p_min[i][j] = INT_MAX;
}
p_min[i][0] = dp[i];
}
dfs(root, -1);
for (int j = 1; j < 32; j++) {
for (int i = 0; i < SZ; i++) {
if (p[i][j - 1] == -1) {
p[i][j] = -1;
p_min[i][j] = INT_MAX;
} else {
p[i][j] = p[p[i][j - 1]][j - 1];
p_min[i][j] = min(p_min[i][j - 1], p_min[p[i][j - 1]][j - 1]);
}
}
}
}
ll query(int a, int b) {
int curr = a;
ll ans = INF;
for(int i = 31; i >= 0; i--){
if(b & (1 << i)) {
ans = min(p_min[curr][i], ans);
curr = p[curr][i];
}
}
assert(curr != -1);
return ans;
}
};
LCA<MX> anc; BLIFT<MX> qry;
int cnt = 0;
void dfs(int v, int p) {
tin[v] = cnt++;
for (pi to : adj[v]) {
if (to.f != p) {
dep[to.f] = dep[v] + to.s;
dfs(to.f, v);
}
}
tout[v] = cnt++;
}
void dfs2(int v, int p) {
if (village[v]) {
dp[v] = dep[v];
cout << "v: " << v << " " << dep[v] << "\n";
}
for (pi to : adj[v]) {
if (to.f != p) {
dfs2(to.f, v);
dp[v] = min(dp[v], dp[to.f]);
}
}
}
bool is_anc(int u, int v) {
if (u == v) return true;
else if((tin[u] < tin[v] && tout[u] > tout[v]) || ((tin[v] < tin[u] && tout[v] > tout[u]))) return true;
return false;
}
vector<pi> ed;
int main(){
ios::sync_with_stdio(false);
cin.tie(0);
int n, s, q, e; cin >> n >> s >> q >> e;
e--;
for (int i = 0; i < n - 1; i++) {
int u, v, w; cin >> u >> v >> w;
u--, v--;
adj[u].pb(mp(v, w)), adj[v].pb(mp(u, w));
anc.addEdge(u, v);
qry.addEdge(u, v);
ed.pb(mp(u, v));
}
for (int i = 0; i < s; i++) {
int x; cin >> x;
x--;
village[x] = true;
}
anc.precomp(e);
dfs(e, -1);
for (int i = 0; i < n; i++) dp[i] = INF;
dfs2(e, -1);
/*
cerr << "DP: " << '\n';
for (int i = 0; i < n; i++) {
cerr << "i, dp[i]: " << i << " " << dp[i] << "\n";
}
*/
for (int i = 0; i < n; i++) if(dp[i] != INF) dp[i] -= 2 * dep[i];
qry.precomp(e, dp);
for (int i = 0; i < q; i++) {
int ind, r; cin >> ind >> r;
ind--, r--;
pi curr = ed[ind];
if (dep[curr.s] < dep[curr.f]) swap(curr.f, curr.s);
// cout << "curr.s, r: " << curr.s + 1 << " " << r + 1 << '\n';
if (is_anc(curr.s, r)) {
int dist = anc.gdep(r) - anc.gdep(curr.f);
// cout << dist << '\n';
ll ret = qry.query(r, dist);
if (ret == INF) {
cout << "oo" << '\n';
}
else {
ret += dep[r];
cout << ret << '\n';
}
}
else {
cout << "escaped" << '\n';
}
}
}
