#include<bits/stdc++.h>
using namespace std;
#define F first
#define S second
#define endl '\n'
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int N = 1e5 + 50;
int n, s, q, r, h[N], st[N], ft[N], t;
ll dis[N];
ll dp[N];
bool mark[N];
pii E[N];
vector<pii> adj[N];
vector<pii> vc[N];
ll out[N];
ll seg[N<<2];
void dfs(int u, int p) {
st[u] = ++t;
h[u] = h[p]+1;
dp[u] = 1e18;
if (mark[u]) dp[u] = 0;
for (pii x:adj[u]) {
int v = x.F, w = x.S;
if (v == p) continue;
dis[v] = dis[u] + w;
dfs(v, u);
dp[u] = min(dp[u], dp[v] + w);
}
ft[u] = t;
}
void build(int u, int tl, int tr) {
if (tl == tr) {
seg[u] = 1e18;
return;
}
int md = (tl+tr)>>1;
int lc = u<<1;
int rc = u<<1|1;
build(lc, tl, md), build(rc, md+1, tr);
seg[u] = min(seg[lc], seg[rc]);
}
ll query(int u, int tl, int tr, int l, int r) {
if (r < tl || tr < l) return 1e18;
if (l <= tl && tr <= r) {
return seg[u];
}
int md = (tl+tr)>>1;
int lc = u<<1;
int rc = u<<1|1;
return min(query(lc, tl, md, l, r), query(rc, md+1, tr, l, r));
}
void upd(int u, int tl, int tr, int id, ll x) {
if (tl == tr) {
seg[u] = x;
return;
}
int md = (tl+tr)>>1;
int lc = u<<1;
int rc = u<<1|1;
if (id <= md) upd(lc, tl, md, id, x);
else upd(rc, md+1, tr, id, x);
seg[u] = min(seg[lc], seg[rc]);
}
void dfs2(int u, int p) {
upd(1, 1, n, h[u], dp[u] - dis[u]);
for (pii p:vc[u]) {
int i = p.F, id= p.S;
int v = (h[E[id].F] < h[E[id].S] ? E[id].S : E[id].F);
if (!(st[v] <= st[u] && ft[v] >= ft[u])) {
out[i] = -1;
continue;
}
out[i] = query(1, 1, n, h[v], h[u]) + dis[u];
}
for (pii x:adj[u]) {
int v = x.F;
if (v==p) continue;
dfs2(v, u);
}
upd(1, 1, n, h[u], 1e18);
}
void solve() {
cin >> n >> s >> q >> r;
for (int i = 1; i <= n-1; i++) {
int u, v, w;
cin >> u >> v >> w;
adj[u].push_back({v, w});
adj[v].push_back({u, w});
E[i] = {u, v};
}
for (int i = 1; i <= s; i++) {
int u;
cin >> u;
mark[u] = 1;
}
for (int i = 1; i <= q; i++) {
int id, u;
cin >> id >> u;
vc[u].push_back({i, id});
}
dfs(r,0);
build(1,1,n);
dfs2(r,0);
for (int i = 1; i <= q; i++) {
if (out[i] == -1) cout << "escaped" << endl;
else if (out[i] >= 1e18) cout << "oo" << endl;
else cout << out[i] << endl;
}
}
int main() {
ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
solve();
return 0;
}
