#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define f first
#define s second
struct Edge{
int a, b, w;
};
const int N = 1e5 + 5;
int n, s, q, ex;
bool shop[N];
int depth[N];
ll d[N];
ll mn[17][N];
int up[17][N];
vector<Edge> e;
vector<vector<int>> cadj;
vector<pair<int, int>> adj[N];
void dfs(int u, int v){
up[0][u] = v;
mn[0][u] = (shop[u] ? 0 : 1e18);
for(auto x : adj[u]){
if(x.f == v) continue;
d[x.f] = d[u] + x.s;
depth[x.f] = depth[u] + 1;
dfs(x.f, u);
mn[0][u] = min(mn[0][u], mn[0][x.f] + x.s);
}
}
int32_t main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n >> s >> q >> ex;
cadj.resize(n);
for(int i = 0; i < n - 1; i++){
int a, b, w;
cin >> a >> b >> w; a--; b--;
adj[a].push_back({b, w});
adj[b].push_back({a, w});
e.push_back({a, b, w});
}
for(int i = 0; i < s; i++){
int x;
cin >> x; x--;
shop[x] = 1;
}
dfs(ex, ex);
for(int i = 0; i < n; i++){
mn[0][i] -= d[i];
}
for(int i = 1; i < 17; i++){
for(int j = 0; j < n; j++){
up[i][j] = up[i - 1][up[i - 1][j]];
mn[i][j] = min(mn[i - 1][j], mn[i - 1][up[i - 1][j]]);
}
}
for(int i = 0; i < n - 1; i++){
if(d[e[i].a] > d[e[i].b]){
swap(e[i].a, e[i].b);
}
}
auto jump = [&](int u, int g) -> int{
for(int i = 0; i < 17; i++){
if(g & (1 << i)){
u = up[i][u];
}
}
return u;
};
auto get_min = [&](int u, int g) -> ll{
ll ret = 1e18;
for(int i = 0; i < 17; i++){
if(g & (1 << i)){
ret = min(ret, mn[i][u]);
u = up[i][u];
}
}
return ret;
};
while(q--){
int u, v;
cin >> u >> v; u--; v--;
int anc = e[u].b, diff = depth[v] - depth[anc];
if(diff < 0 || jump(v, diff) != anc){
cout << "escaped\n";
}
else {
ll val = get_min(v, depth[v] - depth[anc] + 1);
if(val > 1e15) cout << "oo\n";
else cout << val + d[v] << '\n';
}
}
return 0;
}
