#include <bits/stdc++.h>
#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")
using namespace std;
#define X first
#define Y second
#define pb push_back
typedef pair<int, int> ii;
typedef long long ll;
const int maxn = 1e5+5;
int n, k, q, e;
int len[maxn];
vector< ii > way[maxn];
vector< ii > adj[maxn];
int mp[maxn];
int sigan = 0;
struct node
{
int key, pr;
ll val, opt;
node *left, *right;
node(int key, ll val) : key(key), val(val)
{
opt = val;
pr = (rand()<<16)^rand();
left = right = NULL;
}
void calc()
{
opt = val;
if(left) opt = min(left->opt, opt);
if(right) opt = min(right->opt, opt);
}
};
typedef node* ps;
ps merge(ps L, ps R)
{
if(!L || !R) return L?L:R;
if(L->pr> R->pr)
{
L->right = merge(L->right, R);
L->calc();
return L;
}
else
{
R->left = merge(L, R->left);
R->calc();
return R;
}
}
pair<ps, ps> split(ps big, int key)
{
if(!big) return {NULL, NULL};
int here = big->key;
if(here<= key)
{
auto tmp = split(big->right, key);
big->right = tmp.X;
big->calc();
return {big, tmp.Y};
}
else
{
auto tmp = split(big->left, key);
big->left = tmp.Y;
big->calc();
return {tmp.X, big};
}
}
int road[maxn];
void renumb(int u = 1, int p = 0)
{
sigan++;
mp[u] = sigan;
for(auto vv : way[u])
{
int v = vv.X, id = vv.Y;
if(v == p) continue;
// printf("road[%d] = %d\n", id, v);
road[id] = v;
renumb(v, u);
}
}
int cnt[maxn];
bitset<maxn> ban;
void findcnt(int u, int p)
{
cnt[u] = 1;
for(ii vv : adj[u])
{
int v = vv.X;
if(v == p || ban[v]) continue;
findcnt(v, u);
cnt[u] += cnt[v];
}
}
int gimme(int u, int p, int tot)
{
for(ii vv : adj[u])
{
int v = vv.X;
if(v == p || ban[v]) continue;
if(2*cnt[v]> tot)
{
return gimme(v, u, tot);
}
}
return u;
}
bitset<maxn> isshop;
ps root[maxn];
void solve(int u, int p, int cent, ll cur_dep)
{
// printf("go %d %lld\n", u, cur_dep);
if(isshop[u])
{
// add (u, cur_dep) to root[cent]
// printf("beginning to add\n");
auto tmp = split(root[cent], u);
// printf("split ok\n");
ps tmp2 = merge(tmp.X, new node(u, cur_dep));
root[cent] = merge(tmp2, tmp.Y);
// printf("add (%d, %lld) to centroid %d\n", u, cur_dep, cent);
}
for(ii vv : adj[u])
{
int v = vv.X, w = vv.Y;
if(v == p || ban[v]) continue;
solve(v, u, cent, cur_dep+len[w]);
}
}
int par[maxn];
void centroid(int u, int lst)
{
findcnt(u, 0);
// printf("kuy\n");
int tot = cnt[u];
int cent = gimme(u, 0, tot);
par[cent] = lst;
solve(cent, 0, cent, 0);
ban[cent] = true;
for(ii vv : adj[cent])
{
int v = vv.X;
if(ban[v]) continue;
centroid(v, cent);
}
}
ll from[maxn];
int dep[maxn];
int dp[21][maxn];
void util(int u = 1, int p = 0)
{
dep[u] = dep[p]+1;
dp[0][u] = p;
for(int i = 1; i<= 20; i++) dp[i][u] = dp[i-1][dp[i-1][u]];
for(ii vv : adj[u])
{
int v = vv.X, w = vv.Y;
if(v == p) continue;
from[v] = from[u]+len[w];
util(v, u);
}
}
int LCA(int u, int v)
{
if(dep[u]< dep[v]) swap(u, v);
for(int i = 20; i>= 0; i--)
{
int x = dp[i][u];
if(dep[x]>= dep[v]) u = x;
}
if(u == v) return u;
for(int i = 20; i>= 0; i--)
{
if(dp[i][u] == dp[i][v]) continue;
u = dp[i][u]; v = dp[i][v];
}
return dp[0][u];
}
ll getDist(int u, int v)
{
int x = LCA(u, v);
return from[u]+from[v]-from[x]-from[x];
}
int main()
{
scanf("%d %d %d %d", &n, &k, &q, &e);
for(int i = 1; i< n; i++)
{
int u, v, w;
scanf("%d %d %d", &u, &v, &w);
way[u].pb(ii(v, i));
way[v].pb(ii(u, i));
len[i] = w;
}
renumb();
for(int i = 1; i<= n; i++)
{
int u = mp[i];
for(auto vv : way[i])
{
int v = mp[vv.X], id = vv.Y;
assert(u != v);
adj[u].pb(ii(v, id));
adj[v].pb(ii(u, id));
}
}
for(int i = 1; i<= n; i++)
{
sort(adj[i].begin(), adj[i].end());
adj[i].resize(unique(adj[i].begin(), adj[i].end())-adj[i].begin());
}
for(int i = 1; i< n; i++)
{
road[i] = mp[road[i]];
}
for(int i = 1; i<= k; i++)
{
int x; scanf("%d", &x);
isshop[mp[x]] = true;
}
// printf("kuy\n");
centroid(1, 0);
// printf("okay\n");
ban.reset();
findcnt(1, 0);
util();
e = mp[e];
for(int qq = 1; qq<= q; qq++)
{
int r, me; scanf("%d %d", &r, &me);
int st = road[r];
me = mp[me];
bool intree = (st<= me && me<= st+cnt[st]-1);
bool eintree = (st<= e && e<= st+cnt[st]-1);
if(intree == eintree)
{
printf("escaped\n");
continue;
}
int cur = me;
ll best = 1e18;
while(cur> 0)
{
bool curintree = (st<= cur && cur<= st+cnt[st]-1);
if(curintree != intree)
{
cur = par[cur];
continue;
}
ll go = getDist(cur, me);
auto tmp = split(root[cur], st-1);
auto tmp2 = split(tmp.Y, st+cnt[st]-1);
if(intree)
{
if(tmp2.X) best = min(best, go+(tmp2.X)->opt);
}
else
{
if(tmp.X) best = min(best, go+(tmp.X)->opt);
if(tmp2.Y) best = min(best, go+(tmp2.Y)->opt);
}
auto tmp3 = merge(tmp2.X, tmp2.Y);
root[cur] = merge(tmp.X, tmp3);
cur = par[cur];
}
if(best == 1e18) printf("oo\n");
else printf("%lld\n", best);
}
}
