#include <iostream>
#include <fstream>
#include <vector>
#include <cstring>
#include <algorithm>
#include <set>
#include <map>
#include <queue>
#include <list>
#include <utility>
#include <cmath>
#include <numeric>
using namespace std;
typedef long long ll;
#define F first
#define S second
#define pb push_back
#define endl "\n"
#define all(x) x.begin(), x.end()
const int M = 100007;
const ll inf = 1e18;
const ll mod = 1e9 + 7;
const double pi = acos(-1);
const int dx[] = {1, 0, -1, 0}, dy[] = {0, 1, 0, -1};
priority_queue < pair <ll,ll> > q;
vector < pair <ll,ll> > adj[M];
int n, s, qry, root, in[M], out[M], timer, v[M], u[M], dep[M];
ll dist[M][20], mn[M][20], anc[M][20], cost[M];
bool shop[M];
void dfs(int node, int p)
{
cost[node] = (shop[node] ? 0 : 1e18);
in[node] = ++timer;
for(auto i : adj[node]){
if(i.F == p) continue;
dep[i.F] = dep[node] + 1;
anc[i.F][0] = node;
dist[i.F][0] = i.S;
for(int j = 1; j < 20; ++j){
anc[i.F][j] = anc[anc[i.F][j - 1]][j - 1];
dist[i.F][j] = dist[i.F][j - 1] + dist[anc[i.F][j - 1]][j - 1];
}
dfs(i.F, node);
cost[node] = min(cost[node], cost[i.F] + i.S);
}
out[node] = ++timer;
return;
}
void dfs2(int node, int p)
{
for(auto i : adj[node]){
if(i.F == p) continue;
mn[i.F][0] = i.S + cost[node];
for(int j = 1; j < 20; ++j) if(anc[i.F][j]) mn[i.F][j] = min(mn[i.F][j - 1], mn[anc[i.F][j - 1]][j - 1] + dist[i.F][j - 1]);
dfs2(i.F, node);
}
return;
}
int main()
{
ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin >> n >> s >> qry >> root;
for(int i = 1; i < n; ++i){
ll w;
cin >> v[i] >> u[i] >> w;
adj[v[i]].pb({u[i], w});
adj[u[i]].pb({v[i], w});
}
for(int i = 1; i <= s; ++i){
int x;
cin >> x;
shop[x] = 1;
}
dfs(root, 0);
dfs2(root, 0);
int cnt = 1;
while(qry--){
int x, node;
cin >> x >> node;
int p = v[x];
if(anc[u[x]][0] == v[x]) p = u[x];
if(in[node] < in[p] || in[node] > out[p]) cout << "escaped\n";
else{
ll ans = cost[node], road = 0;
for(int j = 19; j >= 0; --j){
if(dep[anc[node][j]] < dep[p]) continue;
ans = min(ans, mn[node][j] + road);
road += dist[node][j];
node = anc[node][j];
}
if(ans == 1e18) cout << "oo\n";
else cout << ans << endl;
}
}
return 0;
}
// Don't forget special cases. (n = 1?)
// Look for the constraints. (Runtime array? overflow?)
