#include <bits/stdc++.h>
using namespace std;
#define F first
#define S second
typedef long long ll;
typedef pair<ll, ll> pi;
ll n, s, q, e, a, b, w, z, r, c[100005];
vector<pi> adj[100005];
pi rs[100005];
ll dfs(ll x, ll p){
ll best = LLONG_MAX/3;
if(x == e) return -1;
for(auto it : adj[x]){
if(it.F == rs[z].F && x == rs[z].S) continue;
if(it.F == rs[z].S && x == rs[z].F) continue;
if(it.F != p){
ll cur = dfs(it.F, x);
if(cur == -1) return cur;
best = min(best, cur+it.S);
}
}
if(c[x]) return 0;
return best;
}
int main(){
cin >> n >> s >> q >> e;
for(ll i = 0; i < n-1; i++){
cin >> a >> b >> w;
adj[a].push_back(pi(b, w));
adj[b].push_back(pi(a, w));
rs[i] = pi(a, b);
}
for(ll i = 0; i < s; i++){ cin >> z; c[z] = 1; }
for(ll i = 0; i < q; i++){
cin >> z >> r; z--;
ll ans = dfs(r, -1);
if(ans == -1) cout << "escaped\n";
else if(ans >= LLONG_MAX/3) cout << "oo\n";
else cout << ans << "\n";
}
}
