#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
#include "debug.h"
#else
#define dbg(...) 47
#endif
constexpr int N = 1e5;
constexpr long long inf = 1e18;
vector<pair<int, int>> g[N];
int par[N], lvl[N], tin[N], tout[N], up[N];
int timer = 0;
void init(int u, int p) {
tin[u] = timer++;
for (auto [v, w] : g[u]) {
if (v != p) {
up[v] = w;
par[v] = u;
lvl[v] = lvl[u] + 1;
init(v, u);
}
}
tout[u] = timer - 1;
}
bool is[N];
long long dp[N];
void dfs(int u, int p) {
if (is[u]) {
dp[u] = 0;
}
for (auto [v, w] : g[u]) {
if (v != p) {
dfs(v, u);
dp[u] = min(dp[u], dp[v] + w);
}
}
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n, k, q, e;
cin >> n >> k >> q >> e;
vector<int> a(n - 1), b(n - 1), w(n - 1);
for (int i = 0; i < n - 1; i++) {
cin >> a[i] >> b[i] >> w[i];
a[i]--; b[i]--;
g[a[i]].push_back({b[i], w[i]});
g[b[i]].push_back({a[i], w[i]});
}
for (int i = 0; i < n; i++) {
dp[i] = inf;
}
for (int i = 0; i < k; i++) {
int s;
cin >> s;
s--;
is[s] = true;
}
e--;
init(e, -1);
dfs(e, -1);
while (q--) {
int i, r;
cin >> i >> r;
i--; r--;
int u = a[i], v = b[i];
if (lvl[u] > lvl[v]) {
swap(u, v);
}
if (tin[v] <= tin[r] && tin[r] <= tout[v]) {
long long res = dp[r], k = 0, prv = dp[r];
while (r != v) {
k += up[r];
r = par[r];
res = min(res, dp[r] + k);
if (res == 0 || r == 0) {
break;
}
if (prv != inf && dp[r] < prv) {
// dbg(dp[r]);
// k += up[r];
// res = min(res, dp[r] + k);
break;
}
prv = dp[r];
}
if (res == inf) {
cout << "oo\n";
} else {
cout << res << '\n';
}
return 0;
} else {
cout << "escaped\n";
}
}
return 0;
}
