#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
#include "debug.h"
#else
#define debug(...) 42
#endif
const int N = 1e5 + 5, LG = 17;
const long long inf = 1e18;
int n, k, q, rt;
int pr[LG][N], h[N], ver[N], w[N];
bool shop[N];
long long dep[N], a[LG][N], best[N];
vector<array<int, 2>> g[N];
bool check(int p, int u) {
for (int i = LG - 1; ~i; --i) {
if (h[u] - (1 << i) >= h[p]) {
u = pr[i][u];
}
}
return u == p;
}
void dfs(int u) {
for (auto [v, id] : g[u]) {
if (v ^ pr[0][u]) {
ver[id] = v;
pr[0][v] = u;
dep[v] = dep[u] + w[id];
h[v] = h[u] + 1;
dfs(v);
best[u] = min(best[u], best[v]);
}
}
best[u] = min(best[u], shop[u] ? dep[u] : inf);
a[0][u] = best[u] == inf ? inf : best[u] - 2 * dep[u];
}
int main() {
ios::sync_with_stdio(false); cin.tie(nullptr);
cin >> n >> k >> q >> rt;
for (int i = 1; i < n; ++i) {
int u, v; cin >> u >> v >> w[i];
g[u].push_back({v, i});
g[v].push_back({u, i});
}
while (k--) {
int u; cin >> u;
shop[u] = 1;
}
memset(best, 0x3f, sizeof(best));
dfs(rt);
for (int i = 1; i < LG; ++i) {
for (int u = 1; u <= n; ++u) {
a[i][u] = min(a[i - 1][u], a[i - 1][pr[i - 1][u]]);
pr[i][u] = pr[i - 1][pr[i - 1][u]];
}
}
while (q--) {
int i, r; cin >> i >> r;
i = ver[i];
if (check(i, r)) {
long long x = inf;
int u = r;
for (int j = LG - 1; ~j; --j) {
if (h[r] - (1 << j) >= h[i] - 1) {
x = min(x, a[j][r]);
r = pr[j][r];
}
}
if (x != inf) {
cout << x + dep[u] << "\n";
} else {
cout << "oo" << "\n";
}
} else {
cout << "escaped" << "\n";
}
}
return 0;
}
