#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
//#pragma GCC optimization("g", on)
//#pragma GCC optimization("03")
//#pragma comment(linker, "/stack:200000000")
//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("inline")
//#pragma GCC optimize("-fgcse,-fgcse-lm")
//#pragma GCC optimize("-ftree-pre,-ftree-vrp")
//#pragma GCC optimize("-ffast-math")
//#pragma GCC optimize("-fipa-sra")
//#pragma GCC optimize("-fpeephole2")
//#pragma GCC optimize("-fsched-spec")
//#pragma GCC optimize("Ofast,no-stack-protector")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
//#pragma GCC optimize("unroll-loops")
#define aboba ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define br break;
#define sp " "
#define en "\n"
#define pb push_back
#define sz size()
#define bg begin()
#define ed end()
#define in insert
#define ss second
#define ff first
#define setp(a) cout << fixed; cout << setprecision(a);
#define all(v) v.begin(), v.end()
typedef long long ll;
typedef long double ld;
typedef pair<ll, ll> pll;
typedef double db;
typedef tree<
long long,
null_type,
less_equal<long long>,
rb_tree_tag,
tree_order_statistics_node_update> orset;
void freopen(string s) { freopen((s + ".in").c_str(), "r", stdin); freopen((s + ".out").c_str(), "w", stdout); }
ll bp(ll x, ll y, ll z) { ll res = 1; while (y) { if (y & 1) { res = (res * x) % z; y--; } x = (x * x) % z; y >>= 1; } return res; }
// C(n, k) = ((fact[n] * bp(fact[k], mod - 2)) % mod * bp(fact[n - k], mod - 2)) % mod;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
ll lcm(ll a, ll b) { return (a / __gcd(a, b)) * b; }
const ll N = 1e5 + 11;
const ll inf = 1e18 + 7;
ll tt = 1;
ll u[N], v[N], w[N];
vector<pll> g[N];
ll dp[N], d[N], dep[N];
bool ok[N];
ll up[N][22], mn[N][22];
void dfs(ll v, ll p) {
dep[v] = dep[p] + 1;
dp[v] = (ok[v] ? 0 : inf);
for (auto it : g[v]) {
ll to = it.ff, h = it.ss;
if (to == p) continue;
d[to] = d[v] + h;
dfs(to, v);
dp[v] = min(dp[v], dp[to] + h);
}
}
void dfs1(ll v, ll p) {
up[v][0] = p;
mn[v][0] = dp[p] - d[p];
for (int i = 1;i <= 20;i++) {
up[v][i] = up[up[v][i - 1]][i - 1];
mn[v][i] = min(mn[v][i - 1], mn[up[v][i - 1]][i - 1]);
}
for (auto it : g[v]) {
ll to = it.ff, h = it.ss;
if (to == p) continue;
dfs1(to, v);
}
}
ll lca(ll u, ll v) {
if (dep[u] < dep[v]) swap(u, v);
ll k = dep[u] - dep[v];
for (int i = 20;i >= 0;i--) {
if (k & (1 << i)) {
u = up[u][i];
}
}
if (u == v) return u;
for (int i = 0;i <= 20;i++) {
if (up[u][i] != up[v][i]) {
u = up[u][i];
v = up[v][i];
}
}
return up[u][0];
}
ll get(ll u, ll v) {
ll ans = dp[v] - d[v];
ll k = dep[v] - dep[u];
for (int i = 20;i >= 0;i--) {
if (k & (1 << i)) {
ans = min(ans, mn[v][i]);
v = up[v][i];
}
}
return (dp[u] == inf ? inf : ans);
}
void solve() {
ll n, k, q, e; cin >> n >> k >> q >> e;
for (int i = 1;i < n;i++) {
cin >> u[i] >> v[i] >> w[i];
g[u[i]].pb({v[i], w[i]});
g[v[i]].pb({u[i], w[i]});
}
for (int i = 1;i <= k;i++) {
ll x; cin >> x;
ok[x] = 1;
}
dp[0] = inf;
dfs(e, 0);
dfs1(e, 0);
for (int i = 1;i < n;i++) {
if (dep[u[i]] > dep[v[i]]) swap(u[i], v[i]);
}
for (int i = 1;i <= q;i++) {
ll x, y; cin >> x >> y;
ll lc = lca(v[x], y);
if (lc != v[x]) {
cout << "escaped" << en;
continue;
}
ll h = get(v[x], y);
if (h == inf) {
cout << "oo" << en;
} else {
cout << h + d[y] << en;
}
}
}
int main() {
aboba
// freopen("cownomics");
// precalc();
// cin >> tt;
for (int i = 1;i <= tt;i++) {
solve();
}
}
