#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<array<int, 3>> mas[100001];
bool shop[100001];
int e;
int dfs(int v, int p, int in, int pgar)
{
if(v==e)
return -1;
int g;
if(shop[v]==1)
g=pgar;
else
g=INT_MAX;
for(auto [vr, gar, id]:mas[v])
{
if(id==in || vr==p)
continue;
else
g=min(g, dfs(vr, v, in, pgar+gar));
}
return g;
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
int n, s, q;
cin >> n >> s >> q >> e;
for(int i=1; i<n; i++)
{
int a, b, w;
cin >> a >> b >> w;
mas[a].pb({b, w, i});
mas[b].pb({a, w, i});
}
for(int i=0; i<s; i++)
{
int a;
cin >> a;
shop[a]=1;
}
for(int i=0; i<q; i++)
{
int in, r;
cin >> in >> r;
int atb=dfs(r, r, in, 0);
if(atb==-1)
cout << "escaped" << endl;
else if(atb==INT_MAX)
cout << "oo" << endl;
else
cout << atb << endl;
}
return 0;
}
