//Make CSP great again
//Vengeance
#include <bits/stdc++.h>
#define TASK "TESTCODE"
#define Log2(x) 31 - __builtin_clz(x)
using namespace std;
const int N = 1e5 , cbit = 16;
int f[N + 1][cbit + 1], depth[N + 1], l[N + 1], r[N + 1], w[N + 1], sz[N + 1], par[N + 1], timer, n, s, q, e;
long long g[N + 1];
bool visited[N + 1];
set<pair<long long, int> > dp[N + 1];
vector<int> adj[N + 1];
void read()
{
cin >> n >> s >> q >> e;
for (int i = 1; i < n; ++ i)
{
cin >> l[i] >> r[i] >> w[i];
adj[l[i]].push_back(i);
adj[r[i]].push_back(i);
}
}
void DFS(int u, int p)
{
for (int x: adj[u])
{
int v = l[x] ^ r[x] ^ u;
if (v == p)
{
continue;
}
depth[v] = depth[u] + 1;
g[v] = g[u] + w[x];
f[v][0] = u;
for (int i = 1; i <= cbit; ++ i)
{
f[v][i] = f[f[v][i - 1]][i - 1];
}
DFS(v, u);
}
}
int LCA(int u, int v)
{
if (depth[v] < depth[u])
{
swap(u, v);
}
int k = depth[v] - depth[u];
for (int i = cbit; i >= 0; -- i)
{
if ((k >> i) & 1)
{
v = f[v][i];
}
}
if (u == v)
{
return u;
}
for (int i = cbit; i >= 0; -- i)
{
if (f[u][i] != f[v][i])
{
u = f[u][i];
v = f[v][i];
}
}
return f[u][0];
}
long long dis(int u, int v)
{
int k = LCA(u, v);
return g[u] + g[v] - 2 * g[k];
}
void CenDFS(int u, int p)
{
sz[u] = 1;
for (int x : adj[u])
{
int v = l[x] ^ r[x] ^ u;
if (v == p || visited[v])
{
continue;
}
CenDFS(v, u);
sz[u] += sz[v];
}
}
int FindCentroid(int u, int p, int s)
{
for (int x : adj[u])
{
int v = l[x] ^ r[x] ^ u;
if (v == p || visited[v])
{
continue;
}
if (sz[v] > s/2)
{
return FindCentroid(v, u, s);
}
}
return u;
}
int BuildCentroid(int u)
{
CenDFS(u, 0);
int root = FindCentroid(u, 0, sz[u]);
visited[root] = true;
for (int x : adj[root])
{
int v = l[x] ^ r[x] ^ root;
if (visited[v])
{
continue;
}
par[BuildCentroid(v)] = root;
}
return root;
}
void update(int u)
{
for (int v = u; v > 0; v = par[v])
{
dp[v].insert({dis(u, v), u});
}
}
int nchain = 1, chain[N + 1], pos[N + 1], head[N + 1];
void preHLD(int u, int p)
{
sz[u] = 1;
for (int x : adj[u])
{
int v = l[x] ^ r[x] ^ u;
if (v == p)
{
continue;
}
preHLD(v, u);
sz[u] += sz[v];
}
}
struct FenwickTree
{
int tree[N + 1];
void add(int pos, int val)
{
for (; pos <= n; pos += (pos & (-pos)))
{
tree[pos] += val;
}
}
int sum(int pos)
{
int ret = 0;
for (; pos > 0; pos -= (pos & (-pos)))
{
ret += tree[pos];
}
return ret;
}
int sum(int l, int r)
{
if (l > r)
{
return 0;
}
return sum(r) - sum(l - 1);
}
} tree;
void HLD(int u, int p)
{
int bigchild = -1;
chain[u] = nchain;
pos[u] = ++timer;
if (head[nchain] == 0)
{
head[nchain] = u;
}
for (int x : adj[u])
{
int v = l[x] ^ r[x] ^ u;
if (v == p)
{
continue;
}
if (bigchild == -1 || sz[bigchild] < sz[v])
{
bigchild = v;
}
}
if (bigchild != -1)
{
HLD(bigchild, u);
}
for (int x : adj[u])
{
int v = l[x] ^ r[x] ^ u;
if (v == bigchild || v == p)
{
continue;
}
++nchain;
HLD(v, u);
}
}
bool reachable(int u, int p)
{
while(chain[u] != chain[p])
{
if (tree.sum(pos[head[chain[u]]], pos[u]) > 0)
{
return false;
}
u = f[head[chain[u]]][0];
}
return tree.sum(pos[p] + 1, pos[u]) == 0;
}
bool reach(int u, int v)
{
int k = LCA(u, v);
return reachable(u, k) && reachable(v, k);
}
int get(int u)
{
long long res = -1;
for (int v = u; v > 0; v = par[v])
{
while(!dp[v].empty() && !reach(dp[v].begin()->second, v))
{
dp[v].erase(dp[v].begin());
}
if (reach(u, v) && !dp[v].empty())
{
if (res == -1 || res > dp[v].begin()->first + dis(u, v))
{
res = dp[v].begin()->first + dis(u, v);
}
}
}
return res;
}
void prepare()
{
DFS(1, 0);
par[BuildCentroid(1)] = 0;
timer = 0;
preHLD(1, 0);
HLD(1, 0);
for (int i = 1; i <= s; ++ i)
{
int u;
cin >> u;
update(u);
}
fill(visited + 1, visited + n, false);
/*for (int i = 1; i <= n; ++ i)
{
cerr << chain[i] << '\n';
}*/
}
void solve()
{
prepare();
while(q--)
{
int i, u;
cin >> i >> u;
if (!visited[i])
{
visited[i] = true;
if (depth[l[i]] > depth[r[i]])
{
swap(l[i], r[i]);
}
tree.add(pos[r[i]], 1);
}
if (reach(u, e))
{
cout << "escaped" << '\n';
continue;
}
long long res = get(u);
if (res == -1)
{
cout << "oo" << '\n';
}
else
{
cout << res << '\n';
}
}
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
if (fopen(TASK".INP", "r"))
{
freopen(TASK".INP", "r", stdin);
//freopen(TASK".OUT", "w", stdout);
}
int t = 1;
bool typetest = false;
if (typetest)
{
cin >> t;
}
for (int __ = 1; __ <= t; ++ __)
{
//cout << "Case " << __ << ": ";
read();
solve();
}
}
