#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int N = 1e6;
ll ver, st, qry, rt;
vector<pair<int, ll>> adj[N];
ll tin[N], tout[N], dist[N], h[N], par[N], dp[N];
bool isst[N];
const int mlg = 32;
ll lca[N][mlg], dpbin[N][mlg];
ll timer = 0;
inline bool is_ancestor(int u, int v)
{
return tin[u] <= tin[v] && tout[u] >= tout[v];
}
void DFS1(int v, int p, int cw)
{
tin[v] = ++timer;
h[v] = h[p] + 1;
dist[v] = cw;
for (auto [n, w] : adj[v])
if (p != n)
{
par[n] = v;
DFS1(n, v, cw + w);
}
if (isst[v])
{
dp[v] = dist[v];
}
else
{
dp[v] = (ll)(1e18);
for (auto [n, w] : adj[v])
if (p != n)
dp[v] = min(dp[v], dp[n]);
}
tout[v] = timer;
}
void preprocess()
{
for (int i = 1; i <= ver; i++)
{
lca[i][0] = par[i];
if (dp[i] >= 1e18)
dpbin[i][0] = 1e18;
else
dpbin[i][0] = dp[i] - 2 * dist[i];
}
for (int vt = 1; vt <= ver; vt++)
{
for (int i = 1; i < mlg; i++)
{
lca[vt][i] = lca[lca[vt][i - 1]][i - 1];
dpbin[vt][i] = min(dpbin[vt][i - 1], dpbin[lca[vt][i - 1]][i - 1]);
}
}
}
ll qryf(int v, int b)
{
if (!is_ancestor(b, v))
{
return -1;
}
int cw = dist[v];
int k = h[v] - h[b];
ll ans = 1e18;
int u = v;
for (int j = 0; (1 << j) <= k; ++j)
if (k >> j & 1)
{
ans = min(ans, dpbin[u][j]);
u = lca[u][j];
}
ans = min(ans, dpbin[u][0]);
// ans += ((ans == 1e18) ? 0 : cw);
return ans + cw;
}
int main()
{
cin >> ver >> st >> qry >> rt;
vector<pair<int, int>> edgelist;
for (int i = 0; i < ver - 1; i++)
{
int u, v;
ll w;
cin >> u >> v >> w;
adj[u].push_back({v, w});
adj[v].push_back({u, w});
edgelist.push_back({u, v});
}
for (int i = 0; i < st; i++)
{
int v;
cin >> v;
isst[v] = 1;
}
DFS1(rt, rt, 0);
preprocess();
while (qry--)
{
int ban, cur;
cin >> ban >> cur;
auto [u, v] = edgelist[ban - 1];
if (h[u] < h[v])
swap(u, v);
ll ans = qryf(cur, u);
if (ans == -1)
cout << "escaped";
else if (ans >= 1e18)
cout << "oo";
else
cout << ans;
cout << '\n';
}
}
