#include <bits/stdc++.h>
#define pb push_back
#define int int64_t
#define pii pair<int, int>
#define X first
#define Y second
#define all(x) (x).begin(),(x).end()
using namespace std;
const int inf = 1e18;
int n, s, q, root;
int timer = 0;
struct edge{
int id, v, w;
};
vector<vector<edge>> g;
vector<int> shops, down, lvl, val, mp, pre, pst;
vector<vector<int>> up, mn;
void p(vector<int>& A){
for(auto e : A)cout << e << ' ';
cout << '\n';
}
void dfs1(int u, int p){
for(auto [id, v, w] : g[u]){
if(v == p)continue;
mp[id] = v;
lvl[v] = lvl[u] + w;
dfs1(v, u);
}
if(shops[u])down[u] = 0;
for(auto [id, v, w] : g[u]){
if(v == p)continue;
down[u] = min(down[u], down[v] + w);
}
val[u] = down[u] - lvl[u];
}
void dfs2(int u, int p){
pre[u] = timer++;
up[0][u] = p;
mn[0][u] = min(val[u], val[up[0][u]]);
for(int i = 1; i< 30; i++){
up[i][u] = up[i-1][up[i-1][u]];
mn[i][u] = min(mn[i-1][u], mn[i-1][up[i-1][u]]);
}
for(auto [id, v, w] : g[u]){
if(v == p)continue;
dfs2(v, u);
}
pst[u] = timer++;
}
int is_anc(int u, int a){
return pre[u] >= pre[a] && pst[u] <= pst[a];
}
void solve(){
cin >> n >> s >> q >> root; root--;
mp.assign(n-1, 0);
g.assign(n, vector<edge>());
shops.assign(n, 0);
down.assign(n, inf);
lvl.assign(n, 0);
val.assign(n, 0);
pre.assign(n, 0);
pst.assign(n, 0);
up.assign(30, vector<int>(n));
mn.assign(30, vector<int>(n, inf));
for(int i = 0; i< n-1; i++){
int a, b, w; cin >> a >> b >> w; a--; b--;
g[a].pb({i, b, w});
g[b].pb({i, a, w});
}
for(int i = 0; i< s; i++){
int c; cin >> c; c--;
shops[c] = 1;
}
dfs1(root, root);
dfs2(root, root);
//p(mp); p(pre); p(pst);
for(int i = 0; i< q; i++){
int id, r; cin >> id >> r; id--; r--;
//cerr << "NODE: " << mp[id] << '\n';
if(!is_anc(r, mp[id])){
cout << "escaped\n";
continue;
}
int start = r;
int ans = val[r];
for(int j = 29; j>= 0; j--){
if(is_anc(up[j][r], mp[id])){
ans = min(ans, mn[j][r]);
r = up[j][r];
}
}
ans += lvl[start];
if(ans == 1e18){
cout << "oo\n";
continue;
}else{
cout << ans << '\n';
}
}
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int t = 1;
//cin >> t;
while(t--)solve();
}
