#include <bits/stdc++.h>
#define int long long
#define sz(a) (int)a.size()
#define all(a) a.begin(), a.end()
using namespace std;
int n,s,e,q;
vector<vector<pair<pair<int,int>,int>>> neigh;
vector<vector<int>> parent;
vector<int> depth;
vector<bool> shop;
vector<int> dist;
vector<int> topdist;
vector<int> road;
vector<vector<pair<int,int>>> child;
const int LOG=31;
int lca(int a, int b){
if(depth[a]>depth[b]) swap(a,b);
int d=depth[b]-depth[a];
for (int i = LOG-1; i>=0; i--)
{
if(d&(1<<i)) b=parent[b][i];
}
if(a==b) return a;
for (int i = LOG-1; i>=0; i--){
if(parent[b][i]!=parent[a][i]){
b=parent[b][i];
a=parent[a][i];
}
}
return parent[a][0];
}
void make_tree(int x, int p){
for (auto u : neigh[x])
{
if(u.first.first==p) continue;
parent[u.first.first][0]=x;
depth[u.first.first]=depth[x]+1;
for (int j = 1; j < LOG; j++) parent[u.first.first][j]=parent[parent[u.first.first][j-1]][j-1];
child[x].push_back({u.first.first,u.first.second});
road[u.second]=u.first.first;
make_tree(u.first.first,x);
}
}
int nthparent(int a, int r){
for (int j = LOG-1; j >= 0; j--) if(r&(1<<j)) a=parent[a][j];
return a;
}
int ddist(int a, int b){
return abs(topdist[a]-topdist[b]);
}
int dfs(int x,int d){
topdist[x]=d;
if(shop[x]) dist[x]=0;
for (auto u : child[x])
{
dist[x]=min(dfs(u.first,d+u.second)+u.second,dist[x]);
}
return dist[x];
}
signed main() {
ios_base::sync_with_stdio(false); cin.tie(nullptr);
cin>>n>>s>>q>>e;
e--;
neigh.resize(n);
depth.resize(n,0);
child.resize(n);
shop.resize(n,false);
dist.resize(n,1e9);
topdist.resize(n,0);
road.resize(n-1,0);
parent.resize(n, vector<int>(LOG,e));
for (int i = 0; i < n-1; i++)
{
int a,b,w; cin >> a >> b >> w;
a--; b--;
neigh[a].push_back({{b,w},i});
neigh[b].push_back({{a,w},i});
}
for (int i = 0; i < s; i++){
int x; cin >> x;
shop[x-1]=true;
}
make_tree(e, e);
dfs(e,0);
topdist[e]=0;
for (int i = 0; i < q; i++){
int I,v; cin >> I >> v;
v--;
I--;
int x=road[I];
if(lca(x,v)==x){
int mn=1e9;
int l=0,r=depth[v]-depth[x];
/*while(r-l>1){
int midU=l+(l+r)/3;
int midD=r-(l+r)/3;
int npU=nthparent(x,midU);
int npD=nthparent(x,midD);
if(dist[npU]+ddist(v,npU)<dist[npD]+ddist(v,npD)){
r=midD;
}else {
l=midU;
}
}*/
for (int k = l; k <= r; k++) {
mn=min(mn, dist[nthparent(v,k)]+ddist(v,nthparent(v,k)));
}
if(mn==1e9) cout << "oo\n";
else cout << mn<<"\n";
}else {
cout << "escaped\n";
}
}
return 0;
}
