#include<bits/stdc++.h>
using namespace std;
#define int long long
#define pii pair<int,int>
const int MAXN = 1e5 + 5;
const int LOG = 20;
int n, s, q, e;
vector<pii> adj[MAXN];
vector<pii> edges;
bool ck[MAXN];
int depth[MAXN];
int d[MAXN];
int up[MAXN][LOG];
int cost[MAXN];
int minn[MAXN][LOG];
int tin[MAXN];
int tout[MAXN];
int timer = 0;
void dfs(int u, int p)
{
tin[u] = ++timer;
depth[u] = depth[p] + 1;
up[u][0] = p;
for (int i = 1; i < LOG; i++)
{
up[u][i] = up[up[u][i-1]][i-1];
}
cost[u] = LLONG_MAX;
if (ck[u])
{
cost[u] = d[u];
}
for (auto [v, w] : adj[u])
{
if (v == p) continue;
d[v] = d[u] + w;
dfs(v, u);
cost[u] = min(cost[u], cost[v]);
}
minn[u][0] = cost[u] - 2 * d[u];
tout[u] = timer;
}
int lift_min(int u, int k)
{
int res = LLONG_MAX;
for (int j = 0; j < LOG; j++)
{
if (k & (1 << j))
{
res = min(res, minn[u][j]);
u = up[u][j];
}
}
return res;
}
signed main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> n >> s >> q >> e;
for (int i = 1; i < n; i++)
{
int u, v, w;
cin >> u >> v >> w;
adj[u].push_back({v, w});
adj[v].push_back({u, w});
edges.push_back({u, v});
}
for (int i = 1; i <= s; i++)
{
int u;
cin >> u;
ck[u] = true;
}
d[e] = 0;
depth[0] = -1;
dfs(e, 0);
for (int j = 1; j < LOG; j++)
{
for (int i = 1; i <= n; i++)
{
if (up[i][j-1] != 0)
{
minn[i][j] = min(minn[i][j-1], minn[up[i][j-1]][j-1]);
}
else
{
minn[i][j] = minn[i][j-1];
}
}
}
while (q--)
{
int qi, qr;
cin >> qi >> qr;
int u = edges[qi-1].first, v = edges[qi-1].second;
if (depth[u] > depth[v]) swap(u, v);
if (tin[v] <= tin[qr] && tout[qr] <= tout[v])
{
int k = depth[qr] - depth[v];
int mn_val = lift_min(qr, k+1);
if (mn_val > 1e15)
{
cout << "oo\n";
}
else
{
cout << mn_val + d[qr] << "\n";
}
}
else
{
cout << "escaped\n";
}
}
}
