using namespace std;
#include <iostream>
#include <algorithm>
#include <vector>
#include <utility>
#include <map>
#include <set>
#include <stack>
#include <queue>
typedef long long LL;
typedef pair<int,int> pii;
#define pb push_back
#define mkp make_pair
#define F first
#define S second
#define iter(x) x.begin(),x.end()
#define REP(n) for (int __=n;__--;)
#define REP0(i,n) for (int i=0;i<n;++i)
#define REP1(i,n) for (int i=1;i<=n;++i)
const int maxn = 1e5+10, mod = 0;
const LL inf = 1e18;
int anc[17][maxn];
LL mx[17][maxn], prefix[maxn];
vector <pii> adj[maxn];
struct EDGE{
int u,v,w;
void input(){
cin >> u >> v >> w;
adj[u].pb(mkp(v,w));
adj[v].pb(mkp(u,w));
}
}edge[maxn];
int dep[maxn], frv[maxn];
bool have_shop[maxn];
void dfs(int x,int fr){
if (fr){
dep[x] = dep[fr] + 1;
anc[0][x] = fr;
prefix[x] = prefix[fr] + frv[x];
}
if (have_shop[x]) mx[0][x] = 0;
else mx[0][x] = inf;
for (auto &[i,w]:adj[x]) if (i != fr){
frv[i] = w;
dfs(i, x);
mx[0][x] = min(mx[0][x], mx[0][i] + w);
}
}
int jump(int x, int k){
if (k) for (int i=0,b=__lg(k);i<=b;++i) if ((k >> i) & 1) x = anc[i][x];
return x;
}
LL premx(int x, int k){
LL ret = mx[0][x];
x = anc[0][x];
if (k) for (int i=0,b=__lg(k);i<=b;++i) if ((k >> i) & 1){
ret = max(ret, mx[i][x]);
x = anc[i][x];
}
return ret;
}
void solve(){
int n, s, q, e;
cin >> n >> s >> q >> e;
REP1(i,n-1){
edge[i].input();
}
REP(s){
int x;
cin >> x;
have_shop[x] = true;
}
dfs(e, 0);
REP1(i, n-1) if (dep[edge[i].v] > dep[edge[i].u]) swap(edge[i].u, edge[i].v);
REP1(i, n) mx[0][i] = prefix[i] - mx[0][i];
REP1(i, 16) REP1(j, n) anc[i][j] = anc[i-1][anc[i-1][j]], mx[i][j] = max(mx[i-1][j], mx[i-1][anc[i-1][j]]);
REP0(i, q){
int c, r;
cin >> c >> r;
c = edge[c].u;
if (dep[r] < dep[c] or jump(r, dep[r] - dep[c]) != c) cout << "escaped\n";
else{
LL ans = prefix[r] - premx(r, dep[r] - dep[c]);
//cout << prefix[r] << ' ' << premx(r, dep[r] - dep[c]) << ' ';
if (ans >= inf/10) cout << "oo\n";
else cout << ans << '\n';
}
}
/*REP0(i, q){
if (o[i] == -1) cout << "escaped\n";
else if (o[i] != inf) cout << o[i] << '\n';
else cout << "oo\n";
}*/
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(0);
solve();
return 0;
}
