#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#define watch(x) cout<<(#x)<<"="<<(x)<<endl
#define mset(d,val) memset(d,val,sizeof(d))
#define setp(x) cout<<fixed<<setprecision(x)
#define forn(i,a,b) for(int i=a;i<b;i++)
#define fore(i,a,b) for(int i=a;i<=b;i++)
#define pb push_back
#define F first
#define S second
#define PI 3.14159265358979323846264338327
#define INF 2e14
#define MOD 998244353
#define pqueue priority_queue
#define fbo find_by_order
#define ook order_of_key
typedef long long ll;
typedef pair<int,ll> ii;
typedef vector<ll> vi;
typedef vector<ii> vii;
typedef unsigned long long ull;
typedef tree<ll, null_type, less<ll>, rb_tree_tag, tree_order_statistics_node_update> pbds;
#define MAXN 100005
#define LG 18
int n,s,q,e;
bool shop[MAXN];
vii adj[MAXN];
ii edges[MAXN];
int depth[MAXN],prt[MAXN][LG+1];
void dfs_prt(int u,int p){
prt[u][0]=p;
forn(j,1,LG){
if(prt[u][j-1]!=-1) prt[u][j]=prt[prt[u][j-1]][j-1];
}
for(ii tmp: adj[u]){
int v=tmp.F;
if(v==p) continue;
depth[v]=depth[u]+1;
dfs_prt(v,u);
}
}
ll dist[MAXN];
void dfs(int u,int p,int xu,int xv){
for(ii tmp: adj[u]){
int v=tmp.F; ll w=tmp.S;
if(v==p) continue;
if((u==xu&&v==xv)||(u==xv&&v==xu)) continue;
dist[v]=dist[u]+w;
dfs(v,u,xu,xv);
}
}
bool findprt(int u,int v){
for(int i=LG-1;i>=0;i--){
if(prt[u][i]!=-1&&depth[prt[u][i]]>=depth[v]) u=prt[u][i];
}
return u==v;
}
void S2()
{
forn(it,0,q)
{
int xe,b; cin>>xe>>b; xe--; b--;
int xu=edges[xe].F, xv=edges[xe].S;
forn(i,0,n) dist[i]=INF;
dist[b]=0;
dfs(b,-1,xu,xv);
ll minn = INF;
forn(i,0,n){
if(shop[i]) minn=min(minn,dist[i]);
}
if(dist[e]<INF) cout<<"escaped"<<'\n';
else if(minn<INF) cout<<minn<<'\n';
else cout<<"oo"<<'\n';
}
}
void S3()
{
forn(it,0,q)
{
int xe,b; cin>>xe>>b; xe--; b--;
int xu=edges[xe].F,xv=edges[xe].S;
if(depth[xu]<depth[xv]) swap(xu,xv); //xu is the lower end
if(depth[b]<depth[xu]){
cout<<"escaped"<<'\n';
continue;
}
if(depth[b]==depth[xu]){
if(b==xu) cout<<0<<'\n';
else cout<<"escaped"<<'\n';
continue;
}
if(findprt(b,xu)) cout<<0<<'\n';
else cout<<"escaped"<<'\n';
}
}
int main()
{
ios_base::sync_with_stdio(0); cin.tie(0);
mset(prt,-1);
cin>>n>>s>>q>>e; e--;
forn(i,0,n-1){
int u,v; ll w;
cin>>u>>v>>w; u--; v--;
adj[u].pb({v,w});
adj[v].pb({u,w});
edges[i]={u,v};
}
forn(i,0,s){
int u; cin>>u; u--;
shop[u]=true;
}
dfs_prt(e,-1);
if(n<=1000&&q<=1000) S2();
else S3();
return 0;
}
