#include <bits/stdc++.h>
using namespace std;
#define el "\n"
#define FOR(i,a,b) for(int i = (a), _b = (b); i <= _b; i++)
#define FORD(i,a,b) for(int i = (a), _b = (b); i >= _b; i--)
#define pb push_back
#define fi first
#define se second
#define all(x) x.begin(),x.end()
#define lg(x) __lg(x)
#define alla(a,n) a+1,a+n+1
#define ll long long
template <class T> bool maxi(T &x, T y) { if(x < y) { x = y ; return true ;} return false;}
template <class T> bool mini(T &x, T y) { if(x > y) { x = y ; return true ;} return false;}
const int N = 1e5 + 2;
const ll inf = 1e18 + 2;
struct Edge
{
int x, y, w;
} E[N];
int n, k, q, tar, shop[N];
vector<pair<int, int>> adj[N];
void inp()
{
cin >> n >> k >> q >> tar;
FOR(i, 1, n - 1) {
int x, y, w; cin >> x >> y >> w;
adj[x].pb({y, w});
adj[y].pb({x, w});
E[i] = {x, y, w};
}
FOR(i, 1, k) cin >> shop[i];
}
/* Try your best
No regrets */
namespace subtask_1
{
int h[N], up[N][21];
ll Val[N];
void dfs(int u, int p)
{
up[u][0] = p;
FOR(j, 1, lg(n)) up[u][j] = up[up[u][j - 1]][j - 1];
for(pair<int, int> x : adj[u]) {
int v = x.first, w = x.second;
if(v == p) continue;
h[v] = h[u] + 1;
Val[v] = Val[u] + w;
dfs(v, u);
}
}
int LCA(int u, int v)
{
if(h[u] < h[v]) swap(u, v);
FORD(j, lg(n), 0) if(h[up[u][j]] >= h[v]) {
u = up[u][j];
}
if(u == v) return u;
FORD(j, lg(n), 0) if(up[u][j] != up[v][j]) {
u = up[u][j];
v = up[v][j];
}
return up[u][0];
}
ll dist(int x, int y)
{
return Val[x] + Val[y] - 2 * Val[LCA(x, y)];
}
bool isMinDist(int x, int y, int id)
{
int u = E[id].x, v = E[id].y, w = E[id].w;
if(dist(x, y) == dist(x, u) + dist(y, v) + w || dist(x, y) == dist(x, v) + dist(y, u) + w) return 1;
return 0;
}
void slv()
{
dfs(1, 1);
while(q--) {
int id, u; cin >> id >> u;
if(!isMinDist(u, tar, id)) {
cout << "escaped" << el;
}
else {
bool oki = 0;
ll ans = inf;
FOR(i, 1, k) {
if(!isMinDist(u, shop[i], id)) {
oki = 1;
mini(ans, dist(u, shop[i]));
}
}
if(oki) cout << ans << el;
else cout << "oo" << el;
}
}
}
}
/* Code slowly, think carefully */
main()
{
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define __Azul__ "valley"
if(fopen(__Azul__".inp", "r")) {
freopen(__Azul__".inp", "r", stdin);
freopen(__Azul__".out", "w", stdout);
}
bool qs = 0;
int T = 1;
if(qs) cin >> T;
while(T--) {
inp();
subtask_1::slv();
}
cerr << "\nTime" << 0.001 * clock() << "s "; return 0;
}
