#include <bits/stdc++.h>
#define fileIO(name) if(fopen(name".inp", "r")) {freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout);}
#define SPEED ios_base :: sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define dbgp(x) cout << #x << " = (" << (x.fi) << ", " << (x.se) << ") "
#define dbg(x) cout << #x << " = " << (x) << ' '
#define rall(x) (x).rbegin(), (x).rend()
#define all(x) (x).begin(), (x).end()
#define sqr(x) (x) * (x)
#define pct __builtin_popcountll
#define lwb lower_bound
#define upb upper_bound
#define eb emplace_back
#define epl emplace
#define mp make_pair
#define fi first
#define se second
using namespace std;
typedef long long ll;
typedef long double ldb;
typedef unsigned int uint;
typedef unsigned long long ull;
typedef pair<ll, ll> pll;
typedef pair<ll, int> pli;
typedef pair<int, ll> pil;
typedef pair<int, int> pii;
typedef pair<ldb, ldb> pld;
typedef pair<double, double> pdd;
template<class T1, class T2> bool minimize(T1 &a, T2 b){
if(a > b){a = b; return true;} return false;
}
template<class T1, class T2> bool maximize(T1 &a, T2 &b){
if(a < b){a = b; return true;} return false;
}
const int N = 1e5 + 10;
const ll oo = 1e16;
int n, nDot, qsn, root, Tin[N], Tout[N], Timer, dep[N];
ll jmp[N][18], dpUp[N][18], sumUp[N][18], dp[N];
pii edge[N];
vector<pil> adj[N];
ll lift(int u, int len){
ll sum = 0, res = oo;
for(int i = 0; i <= 17; ++i) if(len >> i & 1){
minimize(res, dpUp[u][i] + sum);
sum += sumUp[u][i];
u = jmp[u][i];
}
return res;
}
void dfs(int u, int par){
Tin[u] = ++Timer;
for(int i = 0; i < adj[u].size(); ++i){
int v = adj[u][i].fi;
ll w = adj[u][i].se;
if(v == par) continue;
jmp[v][0] = u; sumUp[v][0] = w;
dep[v] = dep[u] + 1;
dfs(v, u);
minimize(dp[u], dp[v] + w);
}
for(int i = 0; i < adj[u].size(); ++i){
int v = adj[u][i].fi;
ll w = adj[u][i].se;
if(v == par) continue;
dpUp[v][0] = min(oo, dp[u] + w);
}
Tout[u] = ++Timer;
}
bool IsAncestor(int u, int v){
return Tin[u] < Tin[v] && Tout[v] < Tout[u];
}
int main(){
SPEED;
cin >> n >> nDot >> qsn >> root;
for(int i = 1; i < n; ++i){
int u, v, w; cin >> u >> v >> w;
adj[u].eb(v, w); adj[v].eb(u, w);
edge[i] = {u, v};
}
for(int i = 1; i <= n; ++i) dp[i] = oo;
for(int i = 1; i <= nDot; ++i){
int v; cin >> v;
dp[v] = 0;
}
dfs(root, 0);
for(int i = 1; i <= 17; ++i){
for(int u = 1; u <= n; ++u) if(jmp[u][i - 1] > 0){
jmp[u][i] = jmp[jmp[u][i - 1]][i - 1];
sumUp[u][i] = sumUp[u][i - 1] + sumUp[jmp[u][i - 1]][i - 1];
dpUp[u][i] = min(dpUp[u][i - 1], sumUp[u][i - 1] + dpUp[jmp[u][i - 1]][i - 1]);
}
}
//dbg(root); cout << '\n';
while(qsn--){
int id, u, cur;
cin >> id >> u;
if(jmp[edge[id].fi][0] == edge[id].se) cur = edge[id].fi;
else cur = edge[id].se;
//dbg(cur); dbg(u);
if(cur == u || IsAncestor(cur, u)){
int len = dep[u] - dep[cur];
ll res = min(dp[u], lift(u, len));
if(res >= oo) cout << "oo";
else cout << res;
cout << '\n';
}
else cout << "escaped\n";
}
return 0;
}
