#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#define LL long long
#define PI pair<int, int>
#define VI vector<int>
#define VB vector<bool>
#define VL vector<LL>
#define VVPI vector<vector<PI>>
using namespace std;
void dfs(int v, int p, const VVPI &G, const VB &shop, VI &depth, VI &tin, VI &tout, VL &dist, VL &closest, VI &parent, int &timer)
{
tin[v] = ++timer;
parent[v] = p;
if (shop[v]) closest[v] = dist[v];
for (auto [u, d] : G[v])
{
if (u == p) continue;
depth[u] = depth[v] + 1;
dist[u] = dist[v] + (LL) d;
dfs(u, v, G, shop, depth, tin, tout, dist, closest, parent, timer);
closest[v] = min(closest[v], closest[u]);
}
tout[v] = ++timer;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int n, s, q, r;
cin >> n >> s >> q >> r;
VVPI G(n + 1);
vector<PI> edges(n);
VB shop(n + 1);
VI depth(n + 1);
VI tin(n + 1);
VI tout(n + 1);
VL dist(n + 1);
VL closest(n + 1, INT64_MAX);
vector<VI> ancestor(20, vector<int>(n + 1));
vector<VL> prefix(20, VL(n + 1));
int a, b, c;
for (int i = 1; i < n; ++i)
{
cin >> a >> b >> c;
G[a].emplace_back(b, c);
G[b].emplace_back(a, c);
edges[i] = {a, b};
}
for (int i = 0; i < s; ++i)
{
cin >> a;
shop[a] = true;
}
dist[r] = 0ll;
int timer = 0;
dfs(r, 0, G, shop, depth, tin, tout, dist, closest, ancestor[0], timer);
for (int v = 1; v <= n; ++v) closest[v] -= 2ll * dist[v];
for (int v = 1; v <= n; ++v) prefix[0][v] = closest[ancestor[0][v]];
for (int l = 1; l < 20; ++l)
{
for (int v = 1; v <= n; ++v)
{
ancestor[l][v] = ancestor[l - 1][ancestor[l - 1][v]];
prefix[l][v] = min(prefix[l - 1][v], prefix[l - 1][ancestor[l - 1][v]]);
}
}
int k, v;
while (q--)
{
cin >> k >> v;
auto [u, w] = edges[k];
if (depth[u] < depth[w]) swap(u, w);
if (tin[u] <= tin[v] && tout[v] <= tout[u])
{
LL res = closest[v];
LL add = dist[v];
for (int l = 19; l >= 0; --l)
{
if (tin[u] <= tin[ancestor[l][v]] && tout[ancestor[l][v]] <= tout[u])
{
res = min(res, prefix[l][v]);
v = ancestor[l][v];
}
}
res += add;
if (res >= 1000000000000000ll) cout << "oo\n";
else cout << res << "\n";
}
else cout << "escaped\n";
}
}
