#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#define ll long long
#define endl '\n'
#define pb push_back
#define fi first
#define se second
#define pii pair<int, int>
using namespace std;
vector<pii> mas[100001];
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
int n, s, q, e;
cin >> n >> s >> q >> e;
set<int> shop;
for(int i=0; i<n-1; i++)
{
int a, b, w;
cin >> a >> b >> w;
mas[a].pb({w, b});
mas[b].pb({w, a});
}
for(int i=0; i<s; i++)
{
int a;
cin >> a;
shop.insert(a);
}
for(int i=0; i<q; i++)
{
int in, r;
cin >> in >> r;
if((in>r && in>=e) || (in<r && in<e))
{
cout << "escaped" << endl;
}
else
{
int atb=INT_MAX;
queue<pii> rinda;
bool biju[n+1]={};
rinda.push({0, r});
biju[r]=1;
while(!rinda.empty())
{
int v=rinda.front().se, w=rinda.front().fi;
rinda.pop();
biju[v]=1;
if(shop.count(v)!=0)
{
atb=w;
break;
}
for(auto x:mas[v])
{
if(biju[x.se]==0 && !(v>x.se && in==x.se))
rinda.push(x);
}
}
if(atb==INT_MAX)
cout << "oo" << endl;
else
cout << atb << endl;
}
}
return 0;
}
