#include <bits/stdc++.h>
using namespace std;
void setup()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
}
int n, s, q, e, a, b, c, pre[20][100000], head[100000], tail[100000];
long long val[20][100000], dist[100000], res;
vector<array<int, 3>> g[100000];
pair<int, int> edges[100000];
bool shop[100000];
inline bool IsPar(int par, int child)
{
return head[par] <= head[child] && tail[child] <= tail[par];
}
inline void DFS(int node, int par)
{
head[node] = a++;
val[0][node] = (shop[node] ? dist[node] : 2e18);
pre[0][node] = par;
for (int i = 1; i < 20; ++i)
{
pre[i][node] = pre[i - 1][pre[i - 1][node]];
}
for (auto &i : g[node])
{
if (i[0] != par)
{
dist[i[0]] = dist[node] + i[1];
DFS(i[0], node);
val[0][node] = min(val[0][node], val[0][i[0]]);
}
}
// cout << node << " " << dist[node] << " " << val[0][node] << "\n";
tail[node] = a - 1;
}
inline void DFS1(int node, int par)
{
val[0][node] -= 2 * dist[node];
for (int i = 1; i < 20; ++i)
{
val[i][node] = min(val[i - 1][node], val[i - 1][pre[i - 1][node]]);
}
for (auto &i : g[node])
{
if (i[0] != par)
{
DFS1(i[0], node);
}
}
}
int main()
{
setup();
cin >> n >> s >> q >> e;
e--;
for (int i = 0; i < n - 1; ++i)
{
cin >> a >> b >> c;
edges[i] = {a - 1, b - 1};
g[a - 1].push_back({b - 1, c, i + 1});
g[b - 1].push_back({a - 1, c, i + 1});
}
while (s--)
{
cin >> a;
shop[a - 1] = true;
}
a = 0;
DFS(e, e);
DFS1(e, e);
// return 0;
while (q--)
{
cin >> a >> b;
a--;
b--;
if (IsPar(edges[a].first, edges[a].second))
{
swap(edges[a].first, edges[a].second);
}
a = edges[a].first;
if (IsPar(a, b))
{
c = b;
res = 2e18;
for (int i = 19; i >= 0; --i)
{
if (IsPar(a, pre[i][b]))
{
res = min(res, dist[c] + val[i][b]);
b = pre[i][b];
}
}
res = min(res, dist[c] + val[0][b]);
cout << (res < 1e15 ? to_string(res) : "oo") << "\n";
}
else
{
cout << "escaped\n";
}
}
return 0;
}
