#include <bits/stdc++.h>
using namespace std;
#define int long long
#define sz(v) (int)v.size()
const int MAXN = 1e5+5, MAX = 16, INF = 1e16;
vector<int> adj[MAXN], w[MAXN], id[MAXN];
int perto[MAXN], rep[MAXN], tin[MAXN], tout[MAXN], t;
int jump[MAX+5][MAXN], mn[MAX+5][MAXN], sp[MAX+5][MAXN];
void dfs(int s, int p){
tin[s] = ++t;
for(int i = 0; i < sz(adj[s]); i++){
int viz = adj[s][i];
if(viz == p)continue;
dfs(viz,s);
perto[s] = min(perto[s], perto[viz] + w[s][i]);
rep[ id[s][i] ] = viz;
}
for(int i = 0; i < sz(adj[s]); i++){
int viz = adj[s][i];
if(viz != p){
jump[0][viz] = s;
mn[0][viz] = min(perto[viz], perto[s] + w[s][i]);
sp[0][viz] = w[s][i];
}
}
tout[s] = t;
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int n,s,q,e; cin>>n>>s>>q>>e;
for(int i = 0; i <= MAX; i++)
for(int j = 1; j <= n; j++)mn[i][j] = INF;
for(int i = 1; i < n; i++){
int a,b,c; cin>>a>>b>>c;
adj[a].push_back(b); w[a].push_back(c); id[a].push_back(i);
adj[b].push_back(a); w[b].push_back(c); id[b].push_back(i);
}
for(int i = 1; i <= n; i++)perto[i] = INF;
for(int i = 1; i <= s; i++){
int c; cin>>c;
perto[c] = 0;
}
dfs(e,0);
for(int i = 1; i <= MAX; i++)
for(int j = 1; j <= n; j++){
if(jump[i-1][j] != 0){
jump[i][j] = jump[i-1][ jump[i-1][j] ];
sp[i][j] = sp[i-1][j] + sp[i-1][ jump[i-1][j] ];
mn[i][j] = min(mn[i-1][j], mn[i-1][ jump[i-1][j] ] + sp[i-1][j]);
}
}
while(q--){
int i,v; cin>>i>>v;
int b = rep[i];
if(tin[b] <= tin[v] && tin[v] <= tout[b]){
int ans = perto[v], s = 0;
for(int j = MAX; j >= 0; j--){
if( tin[ jump[j][v] ] >= tin[b]){
ans = min(ans, mn[j][v]+s);
s += sp[j][v];
v = jump[j][v];
}
}
if(ans == INF)cout<<"oo\n";
else cout<<ans<<"\n";
}else cout<<"escaped\n";
}
}
