#pragma GCC optimize("O1,O2,O3,Ofast,unroll-loops")
#include <bits/stdc++.h>
#include <string>
#include <iostream>
#include <cmath>
#include <numeric>
#include <stack>
#include <queue>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef pair<ld, ld> pd;
typedef vector<int> vi;
typedef vector<bool> vb;
typedef vector<vector<int>> vvi;
typedef vector<vector<pi>> vvpi;
typedef vector<ld> vd;
typedef vector<long long> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
#define FOR(i, a, b) for (int i = a; i < (b); i++)
#define F0R(i, a) for (int i = 0; i < (a); i++)
#define FORd(i, a, b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i, a) for (int i = (a)-1; i >= 0; i--)
#define trav(a, x) for (auto &a : x)
#define uid(a, b) uniform_int_distribution<int>(a, b)(rng)
#define len(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define F first
#define nl endl
#define S second
#define lb lower_bound
#define ub upper_bound
#define aint(x) x.begin(), x.end()
#define raint(x) x.rbegin(), x.rend()
#define ins insert
const int M = 1e9+7;
void init(string name)
{
freopen((name + ".in").c_str(), "r", stdin);
freopen((name + ".out").c_str(), "w", stdout);
}
void fastIO()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
}
int n,s,q,e;
vector<vector<pair<int,pi>>> paths(1e5+10,vector<pair<int,pi>>());
set<int> shops;
vector<set<int>> paths2(1e5+10,set<int>());
ll ans = -1;
void dfs(int pos,int prev,ll dis,int broken){
if(ans == -2)return;
if(pos == e){
ans = -2;
return;
}
if(shops.count(pos)){
if(ans == -1 || ans > dis){
ans = dis;
}
}
for(auto a:paths[pos]){
if(a.F == prev)continue;
if(a.S.S == broken)continue;
dfs(a.F,pos,dis+ll(a.S.F),broken);
}
}
void dfs2(int pos,int prev,set<int> edges){
paths2[pos] = edges;
for(auto a:paths[pos]){
if(a.F == prev)continue;
edges.insert(a.S.S);
dfs2(a.F,pos,edges);
edges.erase(a.S.S);
}
}
void solve()
{
cin >> n >> s >> q >> e;
FOR(i,0,n-1){
int a,b,c;cin >> a >> b >> c;
paths[a].pb({b,{c,i+1}});
paths[b].pb({a,{c,i+1}});
}
FOR(i,0,s){
int a;cin >> a;
shops.insert(a);
}
if(s != n){
FOR(i,0,q){
int a,b;cin >> a >> b;
ans = -1;
dfs(b,-1,0,a);
if(ans == -2)cout << "escaped" << endl;
else if(ans == -1)cout << "oo" << endl;
else cout << ans << endl;
}
return;
}
set<int> edge;
dfs2(e,-1,edge);
FOR(i,0,q){
int a,b;cin >> a >> b;
if(paths2[b].count(a) == 1)cout << "escaped" << endl;
else cout << 0 << endl;
}
}
int main()
{
fastIO();
// init("test");
int t = 1;
// cin >> t;
while (t--)
solve();
return 0;
}
