#include <bits/stdc++.h>
using namespace std;
const int kN = 1e5;
const int kLog = 16;
const int64_t INF = 1e18L;
vector<tuple<int, int, int>> g[1 + kN];
int s[kN], node[kN], depth[1 + kN], anc[1 + kN][1 + kLog];
int64_t dp[1 + kN], bst[1 + kN], best[1 + kN][1 + kLog];
void minSelf(int64_t &x, int64_t y) {
if (y < x) {
x = y;
}
}
void dfs(int u) {
for (int i = 1; i <= kLog; ++i) {
anc[u][i] = anc[anc[u][i - 1]][i - 1];
if (anc[u][i] == 0) {
break;
}
}
bst[u] = INF;
for (auto it : g[u]) {
int v, w, index;
tie(v, w, index) = it;
if (v != anc[u][0]) {
node[index] = v;
depth[v] = depth[u] + 1;
dp[v] = dp[u] + w;
anc[v][0] = u;
dfs(v);
}
}
}
int64_t lift(int &v, int level) {
int64_t ans = bst[v];
for (int i = kLog; i >= 0; --i) {
if (depth[v] - (1 << i) >= level) {
minSelf(ans, best[v][i]);
v = anc[v][i];
}
}
return ans;
}
void testCase() {
int n, m, q, root;
cin >> n >> m >> q >> root;
for (int i = 1; i < n; ++i) {
int u, v, w;
cin >> u >> v >> w;
g[u].emplace_back(v, w, i);
g[v].emplace_back(u, w, i);
}
for (int i = 0; i < m; ++i) {
cin >> s[i];
}
dfs(root);
sort(s, s + m, [&](const int &u, const int &v) -> bool {
return dp[u] < dp[v];
});
for (int i = 0; i < m; ++i) {
int v = s[i];
while (v) {
if (bst[v] != INF) {
break;
}
bst[v] = dp[s[i]] - 2 * dp[v];
v = anc[v][0];
}
}
for (int v = 1; v <= n; ++v) {
best[v][0] = bst[anc[v][0]];
}
for (int j = 1; j <= kLog; ++j) {
for (int i = 1; i <= n; ++i) {
best[i][j] = min(best[i][j - 1], best[anc[i][j - 1]][j - 1]);
}
}
for (int i = 0; i < q; ++i) {
int index, v;
cin >> index >> v;
int64_t ans = dp[v] + lift(v, depth[node[index]]);
if (v != node[index]) {
cout << "escaped\n";
} else if (ans >= INF) {
cout << "oo\n";
} else {
cout << ans << '\n';
}
}
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int tests = 1;
for (int tc = 0; tc < tests; ++tc) {
testCase();
}
return 0;
}
