#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <cmath>
#include <chrono>
#include <ctime>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <deque>
#include <limits>
#include <iomanip>
#include <unordered_set>
#include <unordered_map>
#include <fstream>
#include <functional>
#include <random>
#include <cassert>
#include <bitset>
using namespace std;
typedef long long ll;
typedef long double ld;
#pragma GCC optimize("Ofast")
#define ff first
#define ss second
ll ttt;
const ll INF = 1e18;
const ll MOD = 1e9 + 7;
const ll N = 100007;
const ll LG = 21;
ll n, m, k;
vector<pair<int, ll>>g[N];
int up[N][LG];
ll dist[N][LG]; // the distance between v and up[v][i]
ll dp[N][LG]; // the distance to the closest marked node to v in the subtree of up[v][i]
int tin[N], tout[N];
ll st[N]; // dp for v's subtree
int timer = 0;
bool marked[N];
int lft[N], rgh[N];
void dfs(int v, int par, ll w) {
tin[v] = timer++;
up[v][0] = par;
dist[v][0] = w;
st[v] = INF;
if (marked[v]) {
st[v] = 0;
}
for (auto e : g[v]) {
int to = e.ff;
ll d = e.ss;
if (to != par) {
dfs(to, v, d);
st[v] = min(st[v], st[to] + d);
}
}
tout[v] = timer++;
}
void precalc(int root) {
dfs(root, root, 0);
for (int v = 1; v <= n; v++) {
dp[v][0] = min(st[up[v][0]] + dist[v][0], st[v]);
}
for (int i = 1; i < LG; i++) {
for (int v = 1; v <= n; v++) {
up[v][i] = up[up[v][i - 1]][i - 1];
dist[v][i] = dist[v][i - 1] + dist[up[v][i - 1]][i - 1];
dp[v][i] = min(dp[v][i - 1], dp[up[v][i - 1]][i - 1] + dist[v][i - 1]);
}
}
}
bool is_papa(int v, int u) {
return (tin[v] <= tin[u] && tout[v] >= tout[u]);
}
ll get_ans(int v, int u) {
if (v == u) {
return st[v];
}
ll cur_dist = 0;
ll cur_ans = INF;
for (int i = LG - 1; i >= 0; i--) {
if (!is_papa(up[v][i], u)) {
cur_ans = min(cur_ans, cur_dist + dp[v][i]);
cur_dist += dist[v][i];
v = up[v][i];
}
}
cur_ans = min(cur_ans, cur_dist + dp[v][0]);
return cur_ans;
}
int get_lower(int e) {
if (is_papa(lft[e], rgh[e]))return rgh[e];
return lft[e];
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int root;
cin >> n >> k >> m >> root;
for (int i = 1; i < n; i++) {
int x, y;
cin >> x >> y;
ll w;
cin >> w;
g[x].push_back({ y,w });
g[y].push_back({ x,w });
lft[i] = x;
rgh[i] = y;
}
for (int i = 0; i < k; i++) {
int v;
cin >> v;
marked[v] = true;
}
precalc(root);
for (int i = 0; i < m; i++) {
int e, v;
cin >> e >> v;
int u = get_lower(e);
if (!is_papa(u, v)) {
cout << "escaped\n";
}
else {
ll vl = get_ans(v, u);
if (vl >= INF) {
cout << "oo" << endl;
}
else {
cout << vl << endl;
}
}
}
}
/// ---- - -------- ------ -------- -- - - -
/// Just a reminder. Ubuntu password is I O I
/// ---- - -------- ------ -------- -- - - -
