#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define foru(i, l, r) for(int i=(l); i<=(r); ++i)
#define ford(i, l, r) for(int i=(l); i>=(r); --i)
#define fore(x, v) for(auto &x : v)
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
struct edge {
int u, v, w;
edge(int _u=0, int _v=0, int _w=0) : u(_u), v(_v), w(_w) {}
int o(int t) { return u ^ v ^ t; }
};
const ll LINF = 1e18;
const int N = 1e5+5, LOG = 17, INF = 1e9;
int n, s, q, t;
bool shop[N];
vector<edge> e;
vector<int> graph[N];
int st[N], en[N], high[N], anc[N][LOG], cnt;
ll sum[N][LOG], best[N][LOG], dp[N];
void prep1(int u, int p) {
st[u] = ++cnt;
if (shop[u]) dp[u] = 0;
else dp[u] = LINF;
foru(i, 1, LOG-1) {
anc[u][i] = anc[anc[u][i-1]][i-1];
sum[u][i] = sum[u][i-1] + sum[anc[u][i-1]][i-1];
}
fore(i, graph[u]) {
int v = e[i].o(u);
if (v == p) continue;
anc[v][0] = u;
sum[v][0] = e[i].w;
high[v] = high[u] + 1;
prep1(v, u);
dp[u] = min(dp[u], dp[v] + e[i].w);
}
en[u] = cnt;
}
void prep2(int u, int p) {
best[u][0] = min(dp[u], dp[anc[u][0]] + sum[u][0]);
foru(i, 1, LOG-1) {
best[u][i] = min(best[u][i-1], sum[u][i-1] + best[anc[u][i-1]][i-1]);
}
fore(i, graph[u]) {
int v = e[i].o(u);
if (v == p) continue;
prep2(v, u);
}
}
ll query(int u, int top) {
ll sum_so_far = 0, ret = dp[u];
ford(i, LOG-1, 0) {
if (high[anc[u][i]] >= high[top]) {
ret = min(ret, sum_so_far + best[u][i]);
sum_so_far += sum[u][i];
u = anc[u][i];
}
}
return ret;
}
int main() {
cin >> n >> s >> q >> t;
foru(i, 2, n) {
int u, v, w;
cin >> u >> v >> w;
graph[u].push_back(sz(e));
graph[v].push_back(sz(e));
e.emplace_back(u, v, w);
}
foru(i, 1, s) {
int c;
cin >> c;
shop[c] = 1;
}
dp[0] = LINF;
high[0] = -1;
prep1(t, t);
prep2(t, t);
foru(r, 1, q) {
int i, u;
cin >> i >> u; --i;
if (high[e[i].u] < high[e[i].v]) swap(e[i].u, e[i].v);
int node = e[i].u;
if (st[node] <= st[u] && st[u] <= en[node]) {
ll ans = query(u, node);
if (ans == LINF) cout << "oo\n";
else cout << ans << "\n";
} else cout << "escaped\n";
}
}
