#include <bits/stdc++.h>
#include <ext/pb_ds/detail/standard_policies.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
//#pragma GCC optimize("Ofast")
//#pragma GCC target ("avx2")
#define ll long long
#define ff first
#define ss second
#define int ll
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define pb push_back
#define pii pair <int, int>
#define pdd pair <double, double>
#define vi vector <int>
using namespace std;
using namespace __gnu_pbds;
template <class T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;
const ll inf = 1e15;
const ll mod = 1e9+7;
const int N = 2e5+100;
vector <int> p(N), d(N), ds(N);
vector < vector <pii> > g(N);
vector < vector <int> > up(N, vector <int> (20));
vector <pair <pii, int> > edges(N);
vector <int> c(N);
int n, s, q, r;
void dfs(int v, int pr, int l = 0, int h = 1){
d[v] = h;
ds[v] = l;
up[v][0] = pr;
for (int j = 1; j < 20; ++j) up[v][j] = up[up[v][j-1]][j-1];
for (auto i : g[v]){
int to = i.ff, len = i.ss;
if (to == pr) continue;
dfs(to, v, l + len, h+1);
}
}
int lca(int u, int v){
if (d[u] > d[v]) swap(u, v);
for (int j = 19, H = d[v] - d[u]; H && j >= 0; --j){
if (H < (1 << j)) continue;
H -= (1 << j);
v = up[v][j];
}
if (u == v) return u;
for (int j = 19; j >= 0; --j){
int u1 = up[u][j], v1 = up[v][j];
if (u1 != v1){
u = u1; v = v1;
}
}
return up[u][0];
}
void sol3(){
while (q--){
int ir, v, x, y;
cin >> ir >> v;
x = edges[ir].ff.ff, y = edges[ir].ff.ss;
int w1 = lca(v, x), w2 = lca(v, y);
if (w1 == x && w2 == y) cout << "0\n";
else cout << "escaped\n";
}
}
void sol12(){
while (q--){
int ir, v, x, y;
cin >> ir >> v;
x = edges[ir].ff.ff, y = edges[ir].ff.ss;
vector <int> u(n+10); u[v] = 1;
queue <int> q; q.push(v);
for (int i = 1; i <= n; ++i) d[i] = inf;
d[v] = 0;
while (!q.empty()){
v = q.front(); q.pop();
for (auto [to, len] : g[v]){
if (v == x && to == y || v == y && to == x) continue;
if (u[to]) continue;
u[to] = 1;
d[to] = d[v] + len;
q.push(to);
}
}
if (d[r] != inf){
cout << "escaped\n";
continue;
}
int best = inf;
for (int i = 1; i <= n; ++i)
if (c[i]) best = min(best, d[i]);
if (best == inf) cout << "oo\n";
else cout << best << '\n';
}
}
void solve(){
cin >> n >> s >> q >> r;
for (int i = 1; i < n; ++i){
int a, b, w; cin >> a >> b >> w;
g[a].pb({b, w});
g[b].pb({a, w});
edges[i] = {{a, b}, w};
}
for (int i = 0; i < s; ++i){
int a; cin >> a; c[a] = 1;
}
dfs(r, r);
if (s == n){
sol3(); return;
}
if (n*q <= 1e6){
sol12();
return;
}
}
signed main(){
ios::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
int tt = 1;
while (tt--){
solve();
cout << '\n';
}
}
