#include <iostream>
#include <cmath>
#include<vector>
#include <algorithm>
#include <utility>
#include<stack>
#include<queue>
#include<map>
#include <fstream>
using namespace std;
#define pb push_back
#define mp make_pair
#define ll long long
bool color[100010];
vector<int> upd[100010];
bool ispec[100010];
long long dist[100010];
long long dp[100010];
long long inf=100000000000000000;
int par[100010][30];
long long path[100010][30];
int lvl[100010];
int n,s,q,e;
pair<int,int> edge[100010];
/*struct query{
int color,town,id;
query(){}
query(int color,int town,int id):color(color),town(town),id(id){}
} qlist[100010];*/
struct susjed{
int node,w,id;
susjed(){}
susjed(int node, long long w,int id):node(node),w(w),id(id){}
};
vector<vector<susjed>> adjl;
struct result{
int escape;
long long minw;
}res[100010];
struct in{
int color,town;
in(){}
in(int color, int town):color(color),town(town){}
}qlist[100010];
void dfs( int x, int p, long long len, int depth )
{
dist[x] = len;
lvl[x]=depth;
for( int i=0;i<upd[x].size();i++ ){
int id = upd[x][i];
int c = qlist[ id ].color;
// int c = upd[x][i]
// int id=upd[x][i].id;
res[id].escape = color[c]; /// da li ce pobjec zavisi samo je li dosad naiso na taj color
}
for( int i=0;i<adjl[x].size();i++ ){
if( adjl[x][i].node==p ) continue;
int c = adjl[x][i].id;
color[c]=true; /// ukljucimo edge
dfs( adjl[x][i].node,x, len + adjl[x][i].w, depth+1 );
color[c]=false;
}
}
void dfs2( int x, int p )
{
par[x][0]=p; /// za lca
if( ispec[x] ) dp[x]=dist[x]; /// udaljenost od roota
else dp[x] = inf;
for( int i=0;i<adjl[x].size();i++ ){
if( adjl[x][i].node ==p ) continue;
dfs2( adjl[x][i].node, x );
dp[x]=min(dp[x], dp[ adjl[x][i].node ] ); /// minimum od djece
}
}
/* long long lca( int a, int b )
{
long long res=inf;
if( lvl[a] < lvl[b] ) swap(a,b);
int logg;
for( logg=0;(1<<logg)<=n;logg++ );
logg--;
for( int i=logg;i>=0;i-- ){
if( lvl[a] - ( 1<<i ) >= lvl[b] ) a=par[a][i];
}
if( a==b ) return a;
for( int i=logg;i>=0;i-- ){
if( par[a][i] !=-1 && par[a][i] != par[b][i] ){
a=par[a][i];
b=par[b][i];
}
}
return par[a][0];
}*/
/// dzaba kuco lca kad mi ne treva??? samo mi treba bin lifting
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int u,v;
long long w;
cin>>n>>s>>q>>e;
e--;
adjl.resize(n);
for( int i=0;i<n-1;i++ ){
cin>>u>>v>>w;
u--;
v--;
edge[i] = mp( u,v );
adjl[u].pb( susjed( v,w,i ) );
adjl[v].pb( susjed( u,w,i ) );
}
int tmp;
vector<int> spec;
for( int i=0;i<s;i++ ){
cin>>tmp;
tmp--;
spec.pb( tmp );
ispec[tmp]=true;
}
int l,r;
for( int i=0;i<q;i++ ){
cin>>l>>r;
l--;
r--;
qlist[i] = in(l,r);
upd[r].pb( i );
}
for( int j=0;(1<<j)<=n;j++ ){
for( int i=0;i<n;i++ ) par[i][j]= path[i][j]=-1;
} ///precalc lca
dfs( e,e,0,0 ); /// dfs da offline izracuna samo moze li izaci
dfs2( e,e ); /// drugi dfs, racuna lca dp
for( int i=0;i<n;i++ ) {
if( dp[i]!=inf )
dp[i] -= 2*dist[i]; /// jer dp[i] nam cuva -2*dist[i] + min dist u subtree
}
/// cini se i ovaj dp dobar
/* for( int i = 0;i<n;i++ ){
cout << i << " " << dp[i] << " kontas " <<endl;
}
for( int i =0;i<n;i++ ){
cout << i << " " << dist[i] << " ee " <<endl;
}*/
/// jos ostaje lca da odradimo
for(int i=0;i<n;i++) path[i][0]=dp[i];
for( int j=1;(1<<j)<=n;j++ ){
for( int i=0;i<n;i++ ){
if( par[i][j-1]!=-1 ){
par[i][j] = par[ par[i][j-1] ][j-1];
path[i][j] =min( path[i][j-1], path[ par[i][j-1] ][j-1] );
}
}
}
/* for( int i=0;i<n;i++ ){
cout<<par[i][0] << " " << par[i][1] << " " << path[i][0] << " " <<path[i][1] << " blecak " << dp[i]<<endl;
}*/
//cout << lca( 2,0 ) << " lekceeaa "<<endl;
for( int i=0;i<q;i++ ){
if( res[i].escape == false ){ /// ako nije naisao na edge pokvareni. ovo radi provjerio sam
// cout << i <<endl;
cout << "escaped"<<endl;
}
else{
int p;
int u=qlist[i].town;
long long dd=dist[u];
pair<int,int> ee = edge[ qlist[i].color ]; /// qlist[i].color je index edga
if( lvl[ ee.first ] >= lvl[ ee.second ] ) p = ee.first;
else p=ee.second; /// ovo je dublji vertex medju dva u kveriju, do njega trazimo minimum
long long res=inf;
int logg;
for( logg =0 ;(1<<logg)<=n;logg++ );
logg--;
for( int j=logg;j>=0;j-- ){
if( lvl[u] - (1<<j) >= lvl[p] ){
// cout << i << " " << j << " oko " <<endl;
res=min(res, path[u][j] );
u=par[u][j];
}
}
res=min( res, path[u][0]);
if( res!=inf )
cout<<res+dd<<endl;
else cout <<"oo"<<endl;
// cout << i << " " << p << " " << u << " bruda " <<endl;
}
}
return 0;
}
