#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3")
#define ll long long
#define fori(i,j,k) for(ll i=j; i<=k;i++)
#define study ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define pb push_back
#define all(s) s.begin(),s.end()
#define ins insert
#define ss second
#define ff first
const ll sz=1e5+10;
ll INF=1e18;
ll mod=1e9+7;
ll limit=1e15;
ll tame=0;
vector<vector<pair<ll,ll>>>adj(sz);
vector<vector<ll>>lca(sz,vector<ll>(30,-1)),mini(sz,vector<ll>(30,-1));
vector<ll>in(sz,0),out(sz,0),dp(sz,INF),shops,depth(sz,0);
void restart(ll n){
adj.clear();
in.clear();
out.clear();
adj.assign(n+10,{});
in.assign(n+10,0); out.assign(n+10,0);
tame=0;
}
void dfs(ll t,ll par=-1,ll dap=0){
tame++;
in[t]=tame;
depth[t]=dap;
lca[t][0]=par;
if(count(all(shops),t))
dp[t]=depth[t];
for(auto x: adj[t]){
if(x.ff==par)
continue;
dfs(x.ff,t,dap+x.ss);
dp[t]=min(dp[t],dp[x.ff]);
}
mini[t][0]=dp[t]-2*depth[t];
out[t]=tame;
}
void lcs(ll n){
fori(i,1,29){
fori(j,1,n){
if(lca[j][i-1]==-1)
continue;
lca[j][i]=lca[lca[j][i-1]][i-1];
}
}
fori(i,1,29){
fori(j,1,n){
if(lca[j][i-1]==-1)
continue;
mini[j][i]=min(mini[j][i-1],mini[lca[j][i-1]][i-1]);
}
}
}
void work(){
ll n,m,q,st;
cin>>n>>m>>q>>st;
vector<pair<ll,ll>>ro(n+10);
fori(i,1,n-1){
ll a,b,wei;
cin>>a>>b>>wei;
ro[i]={a,b};
adj[a].pb({b,wei});
adj[b].pb({a,wei});
}
fori(i,1,m){
ll x;
cin>>x;
shops.pb(x);
}
dfs(st,-1,0);
lcs(n);
fori(rando,1,q){
ll ind, qu;
cin>>ind>>qu;
ll a=ro[ind].ff,b=ro[ind].ss;
if(in[a]<=in[qu] and out[a]>=out[qu] and in[b]<=in[qu] and out[b]>=out[qu]){
ll last=a;
if(in[a]<=in[b]){
last=b;
}
if(count(all(shops),qu)){
cout<<0<<endl;
continue;
}
ll oar=qu;
ll ans=mini[qu][0];
fori(i,0,29){
if(lca[qu][i]==-1)
continue;
if(in[lca[qu][i]]>=in[last]){
ans=min(ans,mini[qu][i]);
qu=lca[qu][i];
}
}
ans=min(ans,mini[qu][0]);
ans+=depth[oar];
if(ans>=limit)
cout<<"oo"<<endl;
else
cout<<ans<<endl;
}
else{
cout<<"escaped\n";
}
}
}
int main()
{
// #ifndef LOCAL
// freopen("snowcow.in","r",stdin);
// freopen("snowcow.out","w",stdout);
// #endif
study;
ll t=1;
//cin>>t;
fori(i,1,t){
work();
}
}
