#include <bits/stdc++.h>
using namespace std;
#define pii pair<int, int>
#define fi first
#define se second
const int MX = 3e5 + 10;
const int LG = 19;
const int INF = 1e9 + 7;
int N, S, Q, E, dep[MX], in[MX], out[MX], tim = 0;
int isShop[MX], dist[MX], sp[MX][LG], wt[MX][LG];
vector<pii> adj[MX];
void chmin(int& a, int b){
if(b < a) a = b;
}
void dfs(int u, int v){
in[u] = ++tim;
if(isShop[u]) dist[u] = 0;
for(pii nxt : adj[u]){
if(nxt.fi == v) continue;
dep[nxt.fi] = dep[u] + nxt.se;
dfs(nxt.fi, u);
chmin(dist[u], dist[nxt.fi] + nxt.se);
}
out[u] = tim;
}
void dfs2(int u, int v){
if(dist[u] != INF) dist[u] -= dep[u];
sp[u][0] = v; wt[u][0] = dist[u];
for(int j = 1; j < LG; j++){
sp[u][j] = sp[sp[u][j - 1]][j - 1];
wt[u][j] = min(wt[u][j - 1], wt[sp[u][j - 1]][j - 1]);
}
for(pii nxt : adj[u]){
if(nxt.fi == v) continue;
dfs2(nxt.fi, u);
}
}
void init(){
for(int i = 1; i <= N; i++) dist[i] = INF;
for(int j = 0; j < LG; j++) sp[0][j] = 0, wt[0][j] = INF;
}
vector<pii> edges;
int main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> N >> S >> Q >> E;
for(int i = 1; i < N; i++){
int u, v, w; cin >> u >> v >> w;
adj[u].push_back({v, w});
adj[v].push_back({u, w});
edges.push_back({u, v});
}
for(int i = 1; i <= S; i++){
int C; cin >> C;
isShop[C] = true;
}
init();
dfs(E, 0);
dfs2(E, 0);
for(int i = 0; i < Q; i++){
int I, R, tp, lw; cin >> I >> R; I--;
if(dep[edges[I].fi] < dep[edges[I].se]) tp = edges[I].fi, lw = edges[I].se;
else tp = edges[I].se, lw = edges[I].fi;
if(in[lw] <= in[R] && in[R] <= out[lw]){ // contained
int curr = R, ans = INF;
for(int j = LG - 1; j >= 0; j--){
if(dep[sp[curr][j]] > dep[lw]){
chmin(ans, wt[curr][j]);
curr = sp[curr][j];
}
}
chmin(ans, wt[curr][0]);
curr = sp[curr][0];
chmin(ans, dist[lw]);
if(ans == INF) cout << "oo\n";
else cout << dep[R] + ans << '\n';
}else{
cout << "escaped\n";
}
}
}
