#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 1e5 + 10;
const int LG = 18;
const ll inf = 1e18;
int n, s, q, root, par[N][LG], h[N], wei[N][LG];
ll dist[N];
bool shop[N];
pair<int, int> edge[N];
vector<pair<int, int>> g[N];
void dfs(int v, int p = -1){
dist[v] = inf;
if (shop[v]) dist[v] = 0;
for (auto [w, u] : g[v]){
if (u == p) continue;
h[u] = h[v] + 1;
par[u][0] = v;
wei[u][0] = w;
for (int i = 1; i < LG; i ++){
if (par[u][i - 1] == -1) continue;
par[u][i] = par[par[u][i - 1]][i - 1];
wei[u][i] = wei[u][i - 1] + wei[par[u][i - 1]][i - 1];
}
dfs(u, v);
dist[v] = min(dist[v], dist[u] + w);
}
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
cin >> n >> s >> q >> root;
for (int i = 1; i < n; i ++){
int u, v, w;
cin >> u >> v >> w;
g[u].push_back({w, v});
g[v].push_back({w, u});
edge[i] = {u, v};
}
for (int i = 0; i < s; i ++){
int v;
cin >> v;
shop[v] = 1;
}
dfs(root);
for (int i = 0; i < q; i ++){
int id, v;
cin >> id >> v;
auto [a, b] = edge[id];
if (par[b][0] != a)
swap(a, b);
int d = max(0, h[v] - h[b]);
int anc = v;
for (int i = 0; i < LG; i ++)
if ((1 << i) & d)
anc = par[anc][i];
if (anc != b){
cout << "escaped\n";
continue;
}
if (s == n){
cout << 0 << "\n";
continue;
}
ll cur = dist[v];
ll sm = 0;
// cout << v << " " << cur << endl;
while (v != b){
ll w = wei[v][0];
v = par[v][0];
sm += w;
cur = min(cur, dist[v] + sm);
// cout << v << " " << cur << endl;
}
if (cur == inf)
cout << "oo\n";
else
cout << cur << "\n";
}
}
