#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define F first
#define S second
#define pb push_back
#define endl '\n'
#define Mp make_pair
#define all(x) x.begin(), x.end()
#define debug(x) cerr << #x << " = " << x << endl
#define set_dec(x) cout << fixed << setprecision(x);
#define fast_io ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define file_io freopen("in.txt" , "r+" , stdin) ; freopen("out.txt" , "w+" , stdout);
ll mod = 1e9+7 ;
ll power(ll a, ll b)
{
return (!b ? 1 : (b & 1 ? a * power(a * a % mod, b / 2) % mod : power(a * a % mod, b / 2) % mod));
}
const ll N = 2e5+23 , L = 32, INF = 1e18 ;
ll D[N] , dist[N] , par[N][L] , mn[N][L];
int h[N] , st[N] , ft[N] , t=0;
vector<pii> E;
vector<pii> g[N] ;
int n , s, q, e;
int vis[N];
void dfs(int v, int p=0){
t++;
st[v]=t;
for (auto pp: g[v]){
int u = pp.F , w= pp.S;
if(u!=p){
par[u][0]=v;
h[u]= h[v]+1 ;
dist[u]= dist[v]+w;
dfs(u, v);
}
}
t++;
ft[v]=t;
}
void DFS(int v, int p=0){
if(vis[v]){
D[v]=dist[v];
}
else D[v]=INF;
for (auto pp: g[v]){
int u = pp.F , w= pp.S;
if(u!=p){
DFS(u, v);
D[v]=min(D[v], D[u]);
}
}
}
int main()
{ fast_io
cin>>n>>s>>q>>e;
for (int i=0; i<n-1; i++){
int u , v, w; cin>>v>>u>>w;
g[v].pb({u,w});
g[u].pb({v, w});
E.pb({v, u});
}
for (int i=0; i<s; i++){
int c; cin>>c;
vis[c]=1;
}
dfs(e);
DFS(e);
for (int i=1; i<=n; i++){
D[i]-=(2*dist[i]);
par[i][1]=par[i][0];
par[i][0]=i;
mn[i][0]=D[i];
mn[i][1]= min(D[i] , D[par[i][1]]);
}
for (int j=2; j<L; j++){
for (int i=1; i<=n; i++){
par[i][j]= par[par[i][j-1]][j-1] ;
mn[i][j]= min(mn[i][j-1] , mn[par[i][j-1]][j-1]);
}
}
while(q--){
int l , b;
cin>>l>>b;
l--;
int v=E[l].F , u=E[l].S;
int a=u;
if(h[v]> h[u]){
a=v;
}
if(st[a] <=st[b] && ft[a]>=ft[b]){
ll d= h[a]-h[b];
ll ans= D[b];
//cout<<ans<<" ";
int c=b;
for (int i=L-2; i>=0; i--){
if(d & ( 1<<i) ){
ans= min ( ans, mn [b][i+1]);
b= par[b][i+1];
}
}
if(b!=a)ans= min ( ans, D[b]);
ans+= dist[c];
if( ans> 1e15){
cout<<"oo"<<endl;
}
else cout<<ans<<endl;
}
else cout<<"escaped"<<endl;
}
}
