/**
* Author: Anil Byar
**/
#include <bits/stdc++.h>
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// using namespace __gnu_pbds;
using namespace std;
// template<class T>
// using ordered_set = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define sz(x) (int)(x).size()
#define ft first
#define sd second
#define pb push_back
// Source: https://codeforces.com/blog/entry/68809
// { start
void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '"' << x << '"';}
void __print(const string &x) {cerr << '"' << x << '"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifndef ONLINE_JUDGE
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif
// } end
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<pii> vii;
typedef vector<ll> vl;
typedef vector<pll> vll;
typedef vector<vi> vvi;
typedef vector<vii> vvii;
typedef vector<vl> vvl;
#define dbg if(0)
const ll MOD = 1e9+7;
const ll INFLL = 1e18+5;
const int INF = 1e9;
const int maxN = 1e5+5;
const int maxK = 18;
void printbit(int x, int len) {string s="\n";while(len--){s=((x%2)?'1':'0')+s;x/=2;} cout<<s;}
template<class T>
istream& operator>>(istream&in, vector<T>&v){
for (T& x:v) in>>x;
return in;
}
template<class T>
ostream& operator<<(ostream&out, vector<T>&v){
for (T& x:v) out<<x<<' ';
cout<<'\n';
return out;
}
vii adj[maxN];
int dep[maxN];
int par[maxN][maxK];
ll dist[maxN][maxK];
bool shop[maxN];
ll mnshop[maxN];
ll mnshopup[maxN][maxK];
void dfs(int node, int p = -1){
if (shop[node]) mnshop[node] = 0;
for (auto x:adj[node]){
int v = x.ft, w = x.sd;
if (v==p) continue;
par[v][0] = node;
dist[v][0] = w;
dep[v] = dep[node] + 1;
dfs(v, node);
mnshop[node] = min(mnshop[node], mnshop[v]+w);
}
}
int kup(int x, int k){
for (int i = 0;i<maxK;i++){
if ((k>>i)&1) x = par[x][i];
}
return x;
}
ll getbest(int from, int up){
ll d = 0;
ll ans = mnshop[from];
for (int i = 0;i<maxK;i++){
if (up>>i&1){
ans = min(ans, d+mnshopup[from][i]);
d += dist[from][i];
from = par[from][i];
}
}
return ans;
}
void solve(){
// ll x = 0;
// memset(&x, 127, sizeof(x));
// cout<<x;
int n, s, q, e;
cin>>n>>s>>q>>e;
vii edges(n);
for (int i = 1;i<n;i++){
int u, v, w;cin>>u>>v>>w;
edges[i] = {u, v};
adj[u].emplace_back(v, w);
adj[v].emplace_back(u, w);
}
for (int i = 0;i<s;i++){
int x;cin>>x;
shop[x] = 1;
}
for (int i = 0;i<=n;i++){
for (int j = 0;j<maxK;j++) {
dist[i][j] = INFLL;
mnshopup[i][j] = INFLL;
mnshop[i] = INFLL;
}
}
// memset(dist, 127, sizeof(dist));
// memset(mnshop, 127, sizeof(mnshop));
// memset(mnshopup, 127, sizeof(mnshopup));
dfs(e);
for (int i = 1;i<=n;i++){
mnshopup[i][0] = min(mnshop[i], mnshop[par[i][0]] + dist[i][0]);
}
for (int i = 1;i<maxK;i++){
for (int j = 1;j<=n;j++){
par[j][i] = par[par[j][i-1]][i-1];
dist[j][i] = dist[par[j][i-1]][i-1] + dist[j][i-1];
mnshopup[j][i] = min(mnshopup[j][i-1], mnshopup[par[j][i-1]][i-1] + dist[j][i-1]);
}
}
while(q--){
int i, r;cin>>i>>r;
int v = (dep[edges[i].ft]<dep[edges[i].sd]?edges[i].sd:edges[i].ft);
if (dep[v]>dep[r] || kup(r, dep[r]-dep[v])!=v) { // is v ancestor of r// can also be checked by st < st and en > en
cout<<"escaped\n";
}else {
int up = dep[r]-dep[v];
ll ans = getbest(r, up);
if (ans!=INFLL) cout<<ans<<'\n';
else cout<<"oo\n";
}
}
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
// #define _DEBUG
#ifdef _DEBUG
freopen("input.txt", "r", stdin);
freopen("output.out", "w", stdout);
int tt = clock();
#endif
int t=1, i = 1;
// cin>>t;
while(t--){
// cout<<"Case #"<<i++<<": ";
solve();
cout<<'\n';
}
#ifdef _DEBUG
cerr << "TIME = " << (float)(clock() - tt)/CLOCKS_PER_SEC << endl;
tt = clock();
#endif
}
