#include<bits/stdc++.h>
#pragma optimize ("g",on)
#pragma GCC optimize ("inline")
#pragma GCC optimize ("Ofast")
#pragma GCC optimize ("unroll-loops")
#pragma GCC optimize ("03")
#pragma GCC target ("sse,sse2,sse3,ssse3,sse4,popcnt,abm,avx2,mmx,fma,avx,tune=native")
#pragma comment(linker, "/stack:200000000")
//01001101 01100001 01101011 01101000 01100001 01100111 01100001 01111001
using namespace std;
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define ll long long
#define pb push_back
#define sz(a) a.size()
#define nl '\n'
#define popb pop_back()
#define ld double
#define ull unsigned long long
#define ff first
#define ss second
#define fix fixed << setprecision
#define pii pair<int, int>
#define E exit (0)
#define int long long
const int inf = 1e18, N = 1e6 + 1, mod = 998244353;
vector<pii> dir = {{1, 0}, {0, 1}, {-1, 0}, {0, -1}};
vector<pii> adj[N];
int tin[N], tout[N], timer;
int up[N][20], dist[N];
void dfs(int u, int p) {
tin[u] = timer++;
up[u][0] = p;
for (int i = 1; i < 18; i++) up[u][i] = up[up[u][i - 1]][i - 1];
for (auto e: adj[u]) {
if (e.ff != p) {
dist[e.ff] = dist[u] + e.ss;
dfs(e.ff, u);
}
}
tout[u] = timer++;
}
bool is(int a, int b) {
return tin[a] <= tin[b] && tout[a] >= tout[b];
}
int lca(int a, int b) {
if (is(a, b)) return a;
if (is(b, a)) return b;
for (int i = 17; i >= 0; i--) {
int x = up[a][i];
if (is(x, b)) continue;
a = x;
}
return up[a][0];
}
main() {
//freopen("cowrect.in", "r", stdin);
//freopen("cowrect.out", "w", stdout);
ios_base::sync_with_stdio(NULL);
cin.tie(NULL);
int n, st, q, e;
cin >> n >> st >> q >> e;
int u[n], v[n], w[n];
for (int i = 1; i < n; i++) {
cin >> u[i] >> v[i] >> w[i];
adj[u[i]].pb({v[i], w[i]});
adj[v[i]].pb({u[i], w[i]});
}
dfs(e, e);
int c[st + 1];
for (int i = 1; i <= st; i++) cin >> c[i];
while (q--) {
int i, x;
cin >> i >> x;
if (is(v[i], u[i])) swap(u[i], v[i]);
if (is(v[i], x)) {
if (st == n) {
cout << 0 << nl;
continue;
}
int mn = inf;
for (int j = 1; j <= st; j++) {
if (is(v[i], c[j])) {
int lc = lca(x, c[j]);
mn = min(mn, dist[x] + dist[c[j]] - dist[lc] * 2);
}
}
if (mn == inf) cout << "oo" << nl;
else cout << mn << nl;
}else {
cout << "escaped" << nl;
}
}
}
