#include<bits/stdc++.h>
using namespace std;
#define int int64_t
#define pb push_back
#define st first
#define nd second
#define pii pair<int, int>
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
int n, s, q, e;
vector<pii> G[100009];
bool shop[100009];
int shop_dis[100009];
int dep[100009];
int val[100009];
int tin[100009], tout[100009], T;
pii jp2[100009][20];
int dis(int x, int y) {
return abs(dep[x]-dep[y]);
}
void dfs(int x, int y) {
tin[x] = ++T;
shop_dis[x] = 1e18;
if(shop[x]) shop_dis[x] = 0;
for(auto [z, d]:G[x]) {
if(z==y) continue;
dep[z] = dep[x] + d;
dfs(z, x);
shop_dis[x] = min(shop_dis[x], shop_dis[z]+d);
}
val[x] = shop_dis[x]-dis(x, e);
tout[x] = ++T;
}
void dfs2(int x, int y) {
jp2[x][0] = {y, val[y]};
for(int i=1;i<20;i++) {
jp2[x][i].st = jp2[jp2[x][i-1].st][i-1].st;
jp2[x][i].nd = min(jp2[x][i-1].nd, jp2[jp2[x][i-1].st][i-1].nd);
}
for(auto [z, d]:G[x]) {
if(z!=y) dfs2(z, x);
}
}
bool is_ancestor(int x, int y) {
return tin[x]<=tin[y]&&tout[x]>=tout[y];
}
int solve(int a, int b) {
if(a==b) return val[a];
int ans = val[a];
for(int i=19;i>=0;i--) {
if(!is_ancestor(jp2[a][i].st, b)) {
ans = min(ans, jp2[a][i].nd);
a = jp2[a][i].st;
}
}
ans = min(ans, jp2[a][0].nd);
return ans;
}
vector<pii> edges;
int32_t main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n >> s >> q >> e;
for(int i=0;i<n-1;i++) {
int a, b, c;
cin >> a >> b >> c;
edges.pb({a, b});
G[a].pb({b, c});
G[b].pb({a, c});
}
for(int i=0;i<s;i++) {
int x;
cin >> x;
shop[x] = true;
}
dfs(e, 0);
tout[0] = ++T;
val[e] = 1e18;
dfs2(e, 0);
for(int i=0;i<q;i++) {
int x, a;
cin >> x >> a;
x--;
int b = edges[x].nd;
if(dep[edges[x].st]>dep[edges[x].nd]) b = edges[x].st;
if(a!=b&&!is_ancestor(b, a)) {
cout << "escaped\n";
continue;
}
int ans = solve(a, b);
if(ans>1e17) {
cout << "oo\n";
} else {
cout << ans+dis(a, e) << "\n";
}
}
}
