#include <bits/stdc++.h>
using namespace std;
const int MAX_N = 100'000 + 10;
const int MAX_LG = 17;
const int MAX_Q = 100'000 + 10;
const long long INF = 1e16;
int n, s, q, r, h[MAX_N], par[MAX_N][MAX_LG];
vector<pair<int, int>> adj[MAX_N], edges;
long long d[MAX_N], dp[MAX_N], mn[MAX_N][MAX_LG];
void dfs(int u, int p) {
for (auto [v, w] : adj[u]) {
if (v != p) {
h[v] = h[u] + 1;
d[v] = d[u] + w;
par[v][0] = u;
dfs(v, u);
dp[u] = min(dp[u], dp[v] + w);
}
}
}
int get_par(int u, int k) {
for (int i = 0; k != 0; ++i, k >>= 1) {
if (k & 1) {
u = par[u][i];
}
}
return u;
}
long long get_mn(int u, int k) {
long long res = INF;
for (int i = 0; k != 0; ++i, k >>= 1) {
if (k & 1) {
res = min(res, mn[u][i]);
u = par[u][i];
}
}
return res;
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr), cout.tie(nullptr);
cin >> n >> s >> q >> r;
for (int e = 1; e <= n - 1; ++e) {
int u, v, w;
cin >> u >> v >> w;
edges.push_back({u, v});
adj[u].push_back({v, w});
adj[v].push_back({u, w});
}
fill_n(dp + 1, n, INF);
for (int i = 1; i <= s; ++i) {
int c;
cin >> c;
dp[c] = 0;
}
dfs(r, -1);
for (int u = 1; u <= n; ++u) {
mn[u][0] = dp[u] - d[u];
}
for (int i = 1; i < MAX_LG; ++i) {
for (int u = 1; u <= n; ++u) {
par[u][i] = par[par[u][i - 1]][i - 1];
mn[u][i] = min(mn[u][i - 1], mn[par[u][i - 1]][i - 1]);
}
}
while (q--) {
int e, v;
cin >> e >> v;
auto [eu, ev] = edges[e - 1];
if (h[eu] < h[ev]) swap(eu, ev);
if (h[eu] > h[v] || get_par(v, h[v] - h[eu]) != eu) {
cout << "escaped\n";
} else {
long long res = d[v] + get_mn(v, h[v] - h[eu] + 1);
if (res >= INF / 10) {
cout << "oo\n";
} else {
cout << res << '\n';
}
}
}
}
