#include <bits/stdc++.h>
using namespace std;
#define endl '\n'
#define int long long
const int M = 3e5+5;
int d[M], up[M][40], dp[M], mn[M][40], pr[M], ok[M], dist[M];
vector<array<int, 3>> node[M];
pair<int, int> v[M];
void dfs(int s, int p, int dd = 0, int D = 0) {
d[s] = D;
dist[s] = dd;
up[s][0] = p;
dp[s] = (!ok[s])*LLONG_MAX;
for (auto [i, w, x]:node[s]) {
if (i != p) {
if (v[x].first != s) swap(v[x].first, v[x].second);
dfs(i, s, dd+w, D+1);
dp[s] = min(dp[s], dp[i]+w*(dp[i]!=LLONG_MAX));
}
}
pr[s] = dp[s]-dd*(dp[s]!=LLONG_MAX);
}
int lca(int a, int b) {
if (d[a] < d[b]) swap(a, b);
for (int i = 0; i <= 20; i++) if ((d[a]-d[b])&(1<<i)) a = up[a][i];
int l = 20;
while (a != b) {
while (l >= 0 && up[a][l] == up[b][l]) l--;
if (l < 0) return up[a][0];
a = up[a][l];
b = up[b][l];
}
return a;
}
int mnn(int a, int b) {
int ans = LLONG_MAX;
for (int i = 0; i < 30; i++) {
if ((d[a]-d[b])&(1<<i)) {
ans = min(ans, mn[a][i]);
a = up[a][i];
}
} return ans;
}
signed main() {
cin.tie(0)->sync_with_stdio(0);
int n, s, q, e;
cin >> n >> s >> q >> e;
for (int i = 1; i < n; i++) {
int a, b, c;
cin >> a >> b >> c;
node[a].push_back({b, c, i});
node[b].push_back({a, c, i});
v[i] = {a, b};
}
for (int i = 1; i <= s; i++) {
int x; cin >> x; ok[x] = 1;
}
dfs(e, e);
for (int i = 1; i <= n; i++) mn[i][0] = min(pr[i], pr[up[i][0]]);
for (int j = 1; j <= 30; j++) {
for (int i = 1; i <= n; i++) up[i][j] = up[up[i][j-1]][j-1];
for (int i = 1; i <= n; i++) mn[i][j] = min(mn[i][j-1], mn[up[i][j-1]][j-1]);
}
while (q--) {
int i, a;
cin >> i >> a;
int b = v[i].second;
//if(d[v[i].second]<d[v[i].first]) b = v[i].first;
if (lca(a, b) != b) cout << "escaped" << endl;
else {
int m = mnn(a, b);
if (m == LLONG_MAX) cout << "oo" << endl;
else cout << m+dist[a] << endl;
}
}
return 0;
}
