#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define ld long double
#define pii pair<int,int>
#define pll pair<ll,ll>
#define fi first
#define se second
const int maxN=1e5+5;
const ll inf=2e18;
int n,q,m,e,b[maxN+1],st[maxN+1],en[maxN+1],timer=0,tour[maxN+1],lef[maxN+1],righ[maxN+1];
struct canh
{
int u,v;
ll w;
}a[maxN+1];
vector<pii> adj[maxN+1],vec[maxN+1];
struct query
{
int pos,u;
}p[maxN+1];
ll ans[maxN+1],h[maxN+1];
void pre_dfs(int u,int p)
{
tour[++timer]=u;
st[u]=timer;
for(auto [v,w]:adj[u])
{
if(v!=p)
{
h[v]=h[u]+w;
pre_dfs(v,u);
}
}
en[u]=timer;
}
struct segment
{
struct Node
{
ll s,lazy;
Node()
{
s=inf;
lazy=0;
}
Node(ll S,ll laz)
{
s=S;
lazy=laz;
}
}sum[4*maxN+1];
Node meg(Node x,Node y)
{
Node res;
res.s=min(x.s,y.s);
res.lazy=0;
return res;
}
int l,r;
ll val;
void lazyupdate(int x,int low,int high)
{
if(low==high)
{
return;
}
sum[2*x].s+=sum[x].lazy;
sum[2*x].lazy+=sum[x].lazy;
sum[2*x+1].s+=sum[x].lazy;
sum[2*x+1].lazy+=sum[x].lazy;
sum[x].lazy=0;
}
void Build(int x,int low,int high)
{
if(low==high)
{
sum[x]=Node(h[tour[b[low]]],0);
return;
}
int mid=(low+high)/2;
Build(2*x,low,mid);
Build(2*x+1,mid+1,high);
sum[x]=meg(sum[2*x],sum[2*x+1]);
}
void Update(int x,int low,int high)
{
if(low>r||high<l)
{
return;
}
if(low>=l&&high<=r)
{
sum[x].s+=val;
sum[x].lazy+=val;
return;
}
lazyupdate(x,low,high);
int mid=(low+high)/2;
Update(2*x,low,mid);
Update(2*x+1,mid+1,high);
sum[x]=meg(sum[2*x],sum[2*x+1]);
}
void update_val(int l,int r,ll val)
{
this->l=l;
this->r=r;
this->val=val;
Update(1,1,m);
}
Node get(int x,int low,int high)
{
if(low>r||high<l)
{
return Node(inf,0);
}
if(low>=l&&high<=r)
{
return sum[x];
}
lazyupdate(x,low,high);
int mid=(low+high)/2;
Node get1=get(2*x,low,mid);
Node get2=get(2*x+1,mid+1,high);
return meg(get1,get2);
}
ll query(int l,int r)
{
this->l=l;
this->r=r;
if(l>r)
{
return inf;
}
else return get(1,1,m).s;
}
}str;
bool check(int u,int v)
{
return (st[u]<=st[v]&&st[v]<=en[u]);
}
void dfs(int u,int p)
{
for(auto [j,id]:vec[u])
{
if(check(j,u))
{
ans[id]=min(ans[id],str.query(lef[j],righ[j]));
}
else ans[id]=min(ans[id],min(str.query(1,lef[j]-1),str.query(righ[j]+1,m)));
//cout<<u<<" "<<j<<" "<<id<<" "<<check(j,u)<<" "<<lef[j]<<" "<<righ[j]<<'\n';
}
for(auto [v,w]:adj[u])
{
if(v==p)
{
continue;
}
str.update_val(1,m,w);
str.update_val(lef[v],righ[v],-2*w);
//cout<<u<<" "<<v<<" "<<w<<" "<<str.query(2,2)<<'\n';
dfs(v,u);
str.update_val(1,m,-w);
str.update_val(lef[v],righ[v],2*w);
}
}
int main()
{
//freopen("","r",stdin);
//freopen("","w",stdout);
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin>>n>>m>>q>>e;
for(int i=1;i<n;i++)
{
cin>>a[i].u>>a[i].v>>a[i].w;
adj[a[i].u].push_back({a[i].v,a[i].w});
adj[a[i].v].push_back({a[i].u,a[i].w});
}
pre_dfs(1,0);
for(int i=1;i<=m;i++)
{
int u;
cin>>u;
b[i]=st[u];
}
for(int i=1;i<=q;i++)
{
cin>>p[i].pos>>p[i].u;
int tmp;
if(st[a[p[i].pos].u]>st[a[p[i].pos].v])
{
tmp=a[p[i].pos].u;
}
else tmp=a[p[i].pos].v;
if((check(tmp,p[i].u)&&check(tmp,e))||(!check(tmp,p[i].u)&&!check(tmp,e)))
{
ans[i]=-1;
}
else
{
ans[i]=inf;
vec[p[i].u].push_back({tmp,i});
}
}
sort(b+1,b+m+1);
for(int i=1;i<=n;i++)
{
lef[i]=lower_bound(b+1,b+m+1,st[i])-b;
righ[i]=upper_bound(b+1,b+m+1,en[i])-b-1;
}
str.Build(1,1,m);
/*str.update_val(1,m,3);
cout<<str.query(2,2)<<'\n';*/
dfs(1,0);
for(int i=1;i<=q;i++)
{
if(ans[i]==-1)
{
cout<<"escaped";
}
else if(ans[i]==inf)
{
cout<<"oo";
}
else cout<<ans[i];
cout<<'\n';
}
}
