#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
#include <unordered_map>
#include <unordered_set>
#define ll long long
#define ld long double
#define pl pair<ll, ll>
#define vi vector<ll>
#define vii vector<vi>
#define viii vector<vii>
#define vc vector<char>
#define vcc vector<vc>
#define vp vector<pl>
#define mi map<ll,ll>
#define mc map<char,int>
#define sortx(X) sort(X.begin(),X.end());
#define all(X) X.begin(),X.end()
#define allr(X) X.rbegin(),X.rend()
#define ln '\n'
#define YES {cout << "YES\n"; return;}
#define NO {cout << "NO\n"; return;}
#define MUN {cout << "-1\n"; return;}
using namespace std;
const int MODE = 1e9+7;
const int MXN = 1e5+10, lg = 18;
const ll INF = 1e16;
ll dp[MXN]{}, lvl[MXN]{};
ll val[MXN][lg], best[MXN][lg], par[MXN][lg];
vp adj[MXN];
void dfs(ll n, ll p, ll wp=0) {
lvl[n] = lvl[p]+1;
par[n][0] = p;
val[n][0] = wp;
best[n][0] = dp[p]+wp;
for (int i = 1; i < lg; i++)
{
par[n][i] = par[par[n][i-1]][i-1];
val[n][i] = val[n][i-1] + val[par[n][i-1]][i-1];
best[n][i] = min(best[n][i-1], val[n][i-1] + best[par[n][i-1]][i-1]);
}
for (auto [neg, w] : adj[n]) if (neg != p) {
dfs(neg, n, w);
}
for (auto [neg, w] : adj[n]) if (neg != p) {
dp[n] = min(dp[n], dp[neg]+w);
}
for (int i = 0; i < lg; i++)
{
best[n][i] = min(best[n][i], dp[n]);
}
}
ll kth(ll u, ll k) {
for (int i = 0; i < lg; i++)
if (k & (1<<i)) u = par[u][i];
return u;
}
ll lca(ll u, ll v) {
if (lvl[u] < lvl[v]) swap(u, v);
u = kth(u, lvl[u]-lvl[v]);
if (u == v) return u;
for (int i = lg - 1; i >= 0; i--)
if (par[u][i] != par[v][i]) u = par[u][i], v = par[v][i];
return par[u][0];
}
void solve(int tc) {
ll n, m, q, ro;
cin >> n >> m >> q >> ro;
vp E(n);
for (int i = 0; i < n-1; i++)
{
ll u, v, w; cin >> u >> v >> w;
adj[u].push_back({v, w});
adj[v].push_back({u, w});
E[i+1] = {u, v};
}
fill(dp, dp+MXN, INF);
while (m--)
{
ll u; cin >> u;
dp[u] = 0;
}
dfs(ro, 0);
dfs(ro, 0);
while (q--)
{
ll d, u;
cin >> d >> u;
auto [a, b] = E[d];
if (lvl[a] < lvl[b]) swap(a, b);
if (lca(a, u) != a || lca(b, u) != b) {
cout << "escaped\n";
continue;
}
ll res = dp[u];
ll k = lvl[u] - lvl[a];
ll add = 0;
for (int i = 0; i < lg; i++)
{
if (k & (1<<i)) {
res = min(res, best[u][i] + add);
add += val[u][i];
u = par[u][i];
}
}
if (res == INF) cout << "oo\n";
else cout << res << '\n';
}
}
signed main()
{
ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
int size = 1;
// freopen("kangaroo.in", "r", stdin);
// freopen("kangaroo.out", "w", stdout);
// cin >> size;
for (int i = 1; i <= size ; i++) solve(i);
return 0;
}
