#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 5;
struct edge {int u, v, w;};
int n, q, s, e;
vector<pair<int, int>> adj[maxn];
int dep[maxn], up[maxn][20], tin[maxn], tout[maxn], timer;
long long dist[maxn];
int shops[maxn];
edge edges[maxn];
void dfs(int u, int p)
{
tin[u] = ++timer;
for (auto [v, w] : adj[u])
{
if (v == p) continue;
dep[v] = dep[u] + 1;
dist[v] = dist[u] + w;
up[v][0] = u;
for (int i = 1; i < 20; ++i) up[v][i] = up[up[v][i-1]][i-1];
dfs(v, u);
}
tout[u] = timer;
}
bool isancestor(int u, int v) {return tin[u] <= tin[v] && tout[v] <= tout[u];}
int lca(int u, int v)
{
if (dep[u] < dep[v]) swap(u, v);
int k = dep[u] - dep[v];
for (int i = 0; i < 20; ++i) if (k >> i & 1) u = up[u][i];
if (u == v) return u;
for (int i = 19; i >= 0; --i)
{
if (up[u][i] != up[v][i])
{
u = up[u][i], v = up[v][i];
}
}
return up[u][0];
}
long long calc(int u, int v) {return dist[u] + dist[v] - 2 * dist[lca(u, v)];}
namespace subtask123
{
bool check() { return (n * q <= 1000000) || (s == n); }
void solve()
{
while (q--)
{
int blocked, r; cin >> blocked >> r;
int v = (dep[edges[blocked].u] < dep[edges[blocked].v]) ? edges[blocked].v : edges[blocked].u;
if ((isancestor(v, r) ^ isancestor(v, e)) == 0)
{
cout << "escaped\n";
continue;
}
if (s == n) cout << 0 << '\n';
else
{
long long mindist = LLONG_MAX;
for (int i = 1; i <= s; ++i)
{
if ((isancestor(v, r) ^ isancestor(v, shops[i])) == 0) mindist = min(mindist, calc(shops[i], r));
}
if (mindist == LLONG_MAX) cout << "oo\n";
else cout << mindist << '\n';
}
}
}
}
int main()
{
ios::sync_with_stdio(false); cin.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[i] = {u, v, w};
}
for (int i = 1; i <= s; ++i) cin >> shops[i];
dfs(1, 0);
if (subtask123::check()) subtask123::solve();
return 0;
}
