#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
using namespace std;
#define ff first
#define ss second
#define int long long
#define pb push_back
#define mp make_pair
#define pii pair<int,int>
#define vi vector<int>
#define mii map<int,int>
#define pqb priority_queue<int>
#define pqs priority_queue<int,vi,greater<int> >
#define setbits(x) __builtin_popcountll(x)
#define zrobits(x) __builtin_ctzll(x)
#define mod 1000000007
#define inf 1e18
#define ps(x,y) fixed<<setprecision(y)<<x
#define mk(arr,n,type) type *arr=new type[n];
#define w(x) int x; cin>>x; while(x--)
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
#define fastio ios_base::sync_with_stdio(0); cin.tie(0);
vector<vector<vi>> g;
vector<vi> edge;
vi shops;
int up[100009][21],logk=21,magic[100009],distE[100009],depth[100009],up_magic[100009][21];
void dep(int node,int p,int d,int dd){
distE[node]=d;
depth[node]=dd;
for(auto x:g[node]) if(x[0]!=p) dep(x[0],node,d+x[1],dd+1);
}
void st(int node,int p){
up[node][0]=p;
up_magic[node][0]=magic[p];
for(auto x:g[node]) if(x[0]!=p) st(x[0],node);
}
int dfs(int node,int p){
int ans=inf;
for(auto x:g[node]) if(x[0]!=p) ans=min(ans,dfs(x[0],node));
if(shops[node]==1) ans=distE[node];
return (magic[node]=ans);
}
int lift(int node,int dist){
for(int k=logk-1;k>=0;k--){
if((dist>>k)&1) node=up[node][k];
}
return node;
}
int lca(int a,int b){
a=lift(a,depth[a]-min(depth[a],depth[b]));
b=lift(b,depth[b]-min(depth[a],depth[b]));
if(a==b) return a;
for(int k=logk-1;k>=0;k--){
if(up[a][k]!=up[b][k]) a=up[a][k],b=up[b][k];
}
return up[a][0];
}
int32_t main()
{
fastio;
int n,s,q,e,a,b,w;
cin>>n>>s>>q>>e;
edge.resize(n+1);
g.resize(n+1);
shops.assign(n+1,0);
vector<vi> queries(q);
for(int i=1;i<n;i++){
cin>>a>>b>>w;
g[a].pb({b,w});
g[b].pb({a,w});
edge[i]={a,b};
}
for(int i=0;i<s;i++){
cin>>a;
shops[a]++;
}
for(int i=0;i<q;i++){
cin>>a>>b;
queries[i]={a,b};
}
dep(e,0,0,0);
dfs(e,0);
for(int i=1;i<=n;i++)
if(magic[i]!=inf)
magic[i]=magic[i]-(2*(distE[i]));
magic[0]=inf;
st(e,0);
for(int k=1;k<logk;k++){
for(int i=1;i<=n;i++)
{
up[i][k]=up[up[i][k-1]][k-1];
up_magic[i][k]=min(up_magic[i][k-1],up_magic[up[i][k-1]][k-1]);
}
}
for(int i=0;i<q;i++){
int n1=edge[queries[i][0]][0],n2=edge[queries[i][0]][1],r=queries[i][1];
if(depth[n1]>depth[n2]) swap(n1,n2);
if(lca(r,n2)==n2 )
{
int h = depth[r]-depth[n2],ans=inf;
if(shops[r]) ans=magic[r];
for(int k=logk-1;k>=0;k--){
if((h>>k)&1)
{
ans=min(ans,up_magic[r][k]);
r=up[r][k];
}
}
if(ans==inf) cout<<"oo\n";
else cout<<distE[queries[i][1]]+ans<<"\n";
}
else cout<<"escaped\n";
}
return 0;
}
