#include<bits/stdc++.h>
using namespace std;
#define N 100005
#define int long long
#define log 16
#define oo 1e18
#define fi first
#define se second
typedef pair<int, int> ii;
int par[log + 2][N], mi[log + 2][N], dp[N], q, dep[N], tin[N], tout[N], tim, n, root, m, dis[N];
vector<ii> adj[N];
ii eg[N];
void dfs(int u, int p){
tin[u] = ++tim;
for (auto x : adj[u]){
int v = x.fi, w = x.se;
if (v == p) continue;
dep[v] = dep[u] + 1;
dis[v] = dis[u] + w;
dfs(v, u);
dp[u] = min(dp[u], dp[v] + w);
par[0][v] = u;
}
if (dp[u] != oo) mi[0][u] = dp[u] - dis[u];
tout[u] = tim;
}
bool in(int u, int v){
return (tin[v] >= tin[u] && tout[v] <= tout[u]);
}
int go(int u, int len){
int rt = oo;
for (int k = log; k >= 0; k--){
if ((1 << k) <= len){
len -= (1 << k);
rt = min(rt, mi[k][u]);
u = par[k][u];
}
}
return rt;
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(NULL);
cin >> n >> m >> q >> root;
for (int i = 1; i <= n - 1; i++){
int u, v, w;
cin >> u >> v >> w;
eg[i] = {u, v};
adj[u].push_back({v, w});
adj[v].push_back({u, w});
}
for (int i = 1; i <= n; i++){
mi[0][i] = oo;
dp[i] = oo;
}
for (int i = 1; i <= m; i++){
int val;
cin >> val;
dp[val] = 0;
}
dfs(root, 0);
for (int k = 1; k <= log; k++){
for (int i = 1; i <= n; i++){
par[k][i] = par[k - 1][par[k - 1][i]];
mi[k][i] = min(mi[k - 1][i], mi[k - 1][par[k - 1][i]]);
}
}
while (q--){
int i, r;
cin >> i >> r;
if (dep[eg[i].fi] > dep[eg[i].se]) swap(eg[i].fi, eg[i].se);
if (!in(eg[i].se, r)){
cout << "escaped\n";
continue;
}
int res = dis[r] + go(r, dep[r] - dep[eg[i].se] + 1);
if (res >= oo){
cout << "oo\n";
}
else cout << res << "\n";
}
return 0;
}
