#include <iostream>
#include <vector>
#include <array>
#include <climits>
using namespace std;
const int N = 1e5+5;
const long long INF = 1e18 + 5;
bool shops[N];
vector<array<int, 3> > g[N];
int e, n, s, q;
long long dfs(int u, int p, int blocked, long long curd = 0){
if(u==e)
return -1;
if(u == e)
return -1;
long long dist = (shops[u] ? curd : INF);
for(auto [v, w, id] : g[u]){
if(id==blocked||v==p)
continue;
dist = min(dist, dfs(v,u,blocked, curd+w));
}
return dist;
}
int main()
{
//ios_base::sync_with_stdio(false); cin.tie(nullptr);
cin >> n >> s >> q >> e;
for(int i = 1; i < n; i++){
int u, v, w;
cin >> u >> v >> w;
g[u].push_back({v, w, i});
g[v].push_back({u, w, i});
}
for(int i = 0; i < s; i++){
int c; cin >> c;
shops[c] = 1;
}
while(q--){
int i, r; cin >> i >> r;
long long res = dfs(r,r,i);
if(res == -1)
cout << "escaped\n";
else if (res == INF)
cout << "oo\n";
else
cout << res << '\n';
}
return 0;
}
