#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], num[N];
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, int d=0, int H=0){
par[v][0]=p;
dist[v]=d;
h[v]=H;
st[v]=t;
t++;
for(auto pp: g[v]){
int u=pp.F, w=pp.S;
if(u==p) continue;
dfs(u, v, d+w, H+1);
D[v]=min(D[v], D[u]+w);
}
ft[v]=t;
t++;
}
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({u, v});
}
memset(D, 63 , sizeof(D));
for (int i=1; i<=n; i++)par[i][0]=i;
for(int i=0; i<s; i++){
int C; cin>>C;
D[C]=0;
}
memset(mn , 63 , sizeof(mn));
dfs(e, e) ;
for(int i=0; i<n-1; i++){
if(h[E[i].F] < h[E[i].S]) swap(E[i].F , E[i].S);
}
for(int j=1; j<L; j++){
for(int i=1; i<=n; i++){
par[i][j]=par[par[i][j-1]][j-1];
}
}
for(int i=1; i<=n; i++){
num[i]=D[i]-dist[i];
}
for(int i=0; i<=n; i++){
mn[i][0]=num[par[i][0]];
}
for(int j=1; j<L; j++){
for(int i=0; i<=n; i++){
mn[i][j]=min(mn[i][j-1], mn[par[i][j-1]][j-1]);
}
}
while(q--){
int ed, a; cin>>ed>>a;
ed--;
if(st[E[ed].F] <=st[a] && ft[E[ed].F]>=st[a]){
int b=E[ed].F;
ll ans=num[a];
ll d= h[a]-h[b];
int c=a ;
for(int i=L-1; i>=0; i--){
if(d& ( 1<<i)){
ans= min(ans, mn[a][i]);
a=par[a][i];
}
}
ans=min(ans, num[b]);
//cout<<ans<<" "<<dist[c]<<endl;
ans+=dist[c];
if(ans<=1e18) cout<<ans<<endl;
else cout<<"oo"<<endl;
}
else cout<<"escaped"<<endl;
}
}
