#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx,avx2,fma")
#define int long long
#define F first
#define S second
#define pb push_back
#define endl '\n'
#define all(v) v.begin(),v.end()
#define gcd(a,b) __gcd(a,b)
#define mt make_tuple
#define pqueue priority_queue
typedef pair<int,int> ii;
typedef tuple<int,int,int> iii;
typedef tuple<int,int,int,int> iiii;
typedef vector<int> vi;
typedef vector<bool> vb;
typedef vector<string> vs;
typedef vector<char> vc;
typedef vector<iii> viii;
typedef set<int> si;
typedef vector<ii> vii;
typedef vector<vi> vvi;
typedef vector<si> vsi;
typedef vector<vb> vvb;
typedef vector<vc> vvc;
const int MOD = 1e9 + 7;
const int N = 2e5 + 100;
int n,s,q,e;
vector<viii> adj;
vi v,vis;
int qi,qr;
void _(){
cin >> n >> s >> q >> e; e--;
adj.assign(n+10,viii());
v.assign(n+10,false);
for (int i = 0; i < n-1; i++){
int a,b,w; cin >> a >> b >> w;
a--; b--;
adj[a].emplace_back(b,w,i);
adj[b].emplace_back(a,w,i);
}
for (int i = 0; i < s; i++){
int x; cin >> x; x--;
v[x] = true;
}
for (int i = 0; i < q; i++){
cin >> qi >> qr; qi--; qr--;
pqueue<ii,vii,greater<ii>> pq;
vis.assign(n + 10, INT_MAX);
pq.push({0,qr});
bool escaped = false;
int ans = -1;
while (!pq.empty()){
int d,node; tie(d,node) = pq.top(); pq.pop();
if (vis[node] != INT_MAX) continue;
vis[node] = d;
if (node == e){
escaped = true;
break;
}
if (v[node] && ans == -1) ans = d;
for (auto tp : adj[node]){
int to,w,idx; tie(to,w,idx) = tp;
if (idx == qi) continue;
if (vis[node] != INT_MAX) pq.push({d + w ,to});
}
}
if (escaped) cout << "escaped" << endl;
else {
if (ans != -1) cout << ans << endl;
else cout << "oo" << endl;
}
}
}
int32_t main(){
ios_base::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);
int t = 1;// cin >> t;
while (t--){
_();
}
return 0;
}
