#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 = 1e5 + 100;
int n,s,q,e;
int binlift[N][40];
int binCost[N][40];
vector<viii> adj;
viii edges;
vi cost,v,vis,depth,dist,cnt;
void dfs(int node){
if (vis[node]) return;
vis[node] = true;
cost[node] = INT_MAX;
if (v[node]) {
cost[node] = dist[node];
cnt[node]++;
}
for (auto tp : adj[node]){
int to,d,idx; tie(to,d,idx) = tp;
if (!vis[to]){
binlift[to][0] = node;
dist[to] = dist[node] + d;
depth[to] = depth[node] + 1;
dfs(to);
cnt[node] += cnt[to];
cost[node] = min(cost[node],cost[to]);
}
}
binCost[node][0] = cost[node] - 2*dist[node];
}
int lift(int node,int k){
for (int j = 0; j < 32; j++){
if (k & (1 << j)){
node = binlift[node][j];
if (node == -1) return node;
}
}
return node;
}
int32_t main(){
ios_base::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);
cin >> n >> s >> q >> e; e--;
adj.assign(n+10,viii());
edges.clear();
v.assign(n+10,false);
depth.assign(n+10,false);
vis.assign(n+10,false);
dist.assign(n+10,0);
cost.assign(n+10,0);
cnt.assign(n+10,0);
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);
edges.emplace_back(a,b,w);
}
for (int i = 0; i < s; i++){
int x; cin >> x; x--;
v[x] = true;
}
binlift[e][0] = -1;
depth[e] = 0;
dist[e] = 0;
dfs(e);
for (int i = 0; i < n; i++) cost[i] -= 2 * dist[i];
for (int j = 1; j < 32; j++){
for (int i = 0; i < n; i++){
int nxt = binlift[i][j-1];
if (nxt == -1){
binCost[i][j] = binCost[i][j-1];
binlift[i][j] = -1;
}
else {
binCost[i][j] = min(binCost[i][j-1], binCost[nxt][j-1]);
binlift[i][j] = binlift[nxt][j-1];
}
}
}
for (int i = 0; i < q; i++){
int qi,qr; cin >> qi >> qr; qi--; qr--;
int a,b,w; tie(a,b,w) = edges[qi];
if (depth[a] < depth[b]) swap(a,b);
int diff = depth[qr] - depth[a];
if (diff < 0 || lift(qr,diff) != a) cout << "escaped" << endl;
else {
if (!cnt[a]) cout << "oo" << endl;
else {
int mn = INT_MAX,curr = qr;
for (int j = 0; j < 32; j++){
if ((diff+1) & (1 << j)){
mn = min(mn,binCost[curr][j]);
curr = binlift[curr][j];
if (curr == -1) break;
}
}
cout << mn + dist[qr] << endl;
}
}
}
return 0;
}
