#include<bits/stdc++.h>
using namespace std;
#define debug(n,m) cout<<"["<<#n<<"]->"<<n<<m
#define int long long
#define all(x,off) x.begin()+off,x.end()
#define pb push_back
const int N=1e6+10;
const int inf=9e17;
const int mod=1e9+7;
int n,m,q,k;
int sh[N];
int x[N],y[N],z[N];
vector<array<int,2>> g[N];
int dij(int s,int idx) {
vector<int> d(n+1,inf);
d[s]=0;
priority_queue<array<int,2>> q;
q.push({0,s});
while(!q.empty()) {
auto [dis,u]=q.top();
q.pop();
if (-dis>d[u]) continue;
for (auto [v,w]:g[u]) {
if (min(u,v)==x[idx]&&max(u,v)==y[idx]) continue;
if (d[v]>d[u]+w) {
d[v]=d[u]+w;
q.push({-d[v],v});
}
}
}
if (d[k]!=inf) return -1;
int dis=inf;
for (int i=1;i<=n;++i) {
if (sh[i]) dis=min(dis,d[i]);
}
return dis;
}
void levi() {
cin>>n>>m>>q>>k;
for (int i=1;i<=n-1;++i) {
int u,v,w;
cin>>u>>v>>w;
if (u>v) swap(u,v);
x[i]=u;
y[i]=v;;z[i]=w;
g[u].pb({v,w});
g[v].pb({u,w});
}
for (int i=1,x;i<=m;++i) {
cin>>x;
sh[x]=1;
}
for (int j=1;j<=q;++j) {
int i,s;
cin>>i>>s;
int res=dij(s,i);
if (res==-1) {
cout<<"escaped\n";
continue;
}
if (res==inf) {
cout<<"oo\n";
continue;
}
cout<<res<<'\n';
}
}
int32_t main() {
ios_base::sync_with_stdio(0);
cin.tie(0);int tt=1;//cin>>tt;
while (tt--) levi();
}
/*
*/
