#include <bits/stdc++.h>
using namespace std;
#define ll long long
const int nx = 1e5 + 5;
const ll maxDist = (1000000000LL) * (1e5);
int n, s, q, e;
vector<pair<int,ll>> adj[nx];
int u[nx], v[nx];
int tin[nx], tout[nx], timer = 0;
int depth[nx], pa[nx];
ll dist[nx], best[nx], opt[nx];
ll dp[nx][18];
ll dp2[nx][18];
void dfs(int u) {
tin[u] = timer++;
for (auto [v, w] : adj[u]) {
if (pa[u] == v) continue;
dist[v] = dist[u] + w;
depth[v] = depth[u] + 1;
pa[v] = u;
dfs(v);
}
tout[u] = timer++;
}
ll solve(int u) {
ll ans = 1e18;
for (auto [v, w] : adj[u]) {
if (pa[u] == v) continue;
ans = min(ans, solve(v) + w);
}
return best[u] = min(best[u], ans);
}
ll query(int u, int k) {
if (k == 0) return opt[u];
ll ans = 1e18;
for (int i = 0; (1 << i) <= k; i++) {
if ((1 << i) & k) {
ans = min(ans, dp2[u][i]);
u = dp[u][i];
}
}
return ans;
}
int main() {
ios_base::sync_with_stdio(0), cin.tie(0);
cin >> n >> s >> q >> e;
pa[e] = e;
for (int i = 1; i <= n - 1; i++) {
cin >> u[i] >> v[i];
int w;
cin >> w;
adj[u[i]].emplace_back(v[i], w);
adj[v[i]].emplace_back(u[i], w);
}
for (int i = 1; i <= n; i++) best[i] = dist[i] = 1e18;
dist[e] = 0;
while (s--) {
int c; cin >> c;
best[c] = 0;
}
dfs(e);
solve(e);
for (int i = 1; i <= n; i++) opt[i] = best[i] - dist[i];
for (int u = 1; u <= n; u++) {
dp[u][0] = pa[u];
dp2[u][0] = min(opt[u], opt[pa[u]]);
}
for (int k = 1; (1 << k) <= n; k++) {
for (int u = 1; u <= n; u++) {
dp[u][k] = dp[dp[u][k-1]][k-1];
}
for (int u = 1; u <= n; u++) {
dp2[u][k] = min(dp2[u][k-1], dp2[dp[u][k-1]][k-1]);
}
}
while (q--) {
int i, k;
cin >> i >> k;
int root;
if (depth[u[i]] < depth[v[i]]) root = v[i];
else root = u[i];
//printf("%d %d\n", root, k);
if (!(tin[root] <= tin[k] && tin[k] <= tout[root])) {
cout << "escaped\n";
continue;
}
ll ans = dist[k] + query(k, depth[k] - depth[root]);
//printf("ans = %lld + %lld = %lld\n", dist[k] + query(k, depth[k] - depth[root]), ans);
if (ans > maxDist) cout << "oo\n";
else cout << ans << "\n";
}
}
/*
5 2 3 1
1 2 3
1 3 2
3 4 1
3 5 2
2
4
2 2
2 5
4 5
*/
