#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int MAXN = 1e5;
const ll INF = 1e15;
struct Edge { int u, v, w; };
int N, S, Q, E;
vector<pii> adj[MAXN+10];
Edge edge[MAXN+10];
int C[MAXN+10];
int L[MAXN+10], R[MAXN+10], pos[MAXN+10], cnt;
bool reach(int I, int u, int v)
{
bool a=(L[edge[I].v]<=L[u] && L[u]<=R[edge[I].v]);
bool b=(L[edge[I].v]<=L[v] && L[v]<=R[edge[I].v]);
return a==b;
}
void dfs(int now, int bef)
{
L[now]=R[now]=++cnt;
pos[L[now]]=now;
for(auto nxt : adj[now])
{
if(nxt.first==bef) continue;
dfs(nxt.first, now);
R[now]=max(R[now], R[nxt.first]);
}
}
int sz[MAXN+10], cenpar[MAXN+10], cendep[MAXN+10];
ll dist[MAXN+10][30];
pll D1[MAXN+10], D2[MAXN+10];
bool del[MAXN+10];
void getsz(int now, int bef)
{
sz[now]=1;
for(auto nxt : adj[now])
{
if(nxt.first==bef) continue;
if(del[nxt.first]) continue;
getsz(nxt.first, now);
sz[now]+=sz[nxt.first];
}
}
int getcen(int now, int bef, int S)
{
for(auto nxt : adj[now])
{
if(nxt.first==bef) continue;
if(del[nxt.first]) continue;
if(sz[nxt.first]>S/2) return getcen(nxt.first, now, S);
}
return now;
}
pll dfs2(int now, int bef, ll depth, int root, int cdep)
{
dist[now][cdep]=depth;
pll ret={INF, INF};
if(C[now]) ret=min(ret, {depth, root});
for(auto nxt : adj[now])
{
if(nxt.first==bef) continue;
if(del[nxt.first]) continue;
ret=min(ret, dfs2(nxt.first, now, depth+nxt.second, root, cdep));
}
return ret;
}
int decomp(int now, int bef, int dep)
{
getsz(now, now);
now=getcen(now, now, sz[now]);
del[now]=true;
cendep[now]=dep;
if(bef) cenpar[now]=bef;
else cenpar[now]=now;
D1[now]={INF, INF};
D2[now]={INF, INF};
for(auto nxt : adj[now])
{
if(del[nxt.first]) continue;
int nxtcen=decomp(nxt.first, now, dep+1);
pll t=dfs2(nxt.first, now, nxt.second, nxtcen, dep);
if(t<D1[now]) D2[now]=D1[now], D1[now]=t;
else if(t<D2[now]) D2[now]=t;
}
//printf("%d : %lld %lld / %lld %lld\n", now, D1[now].first, D1[now].second, D2[now].first, D2[now].second);
del[now]=false;
return now;
}
ll query(int now, int cut)
{
ll ans=INF;
int bef=now, beg=now;
while(1)
{
if(reach(cut, beg, now))
{
if(D1[now].second!=bef) ans=min(ans, D1[now].first+dist[beg][cendep[now]]);
else ans=min(ans, D2[now].first+dist[beg][cendep[now]]);
if(C[now]) ans=min(ans, dist[beg][cendep[now]]);
}
if(now==cenpar[now]) break;
bef=now;
now=cenpar[now];
}
return ans;
}
int main()
{
int i, j;
scanf("%d%d%d%d", &N, &S, &Q, &E);
for(i=1; i<N; i++)
{
int u, v, w;
scanf("%d%d%d", &u, &v, &w);
adj[u].push_back({v, w});
adj[v].push_back({u, w});
edge[i]={u, v, w};
}
for(i=1; i<=S; i++)
{
int t;
scanf("%d", &t);
C[t]=1;
}
dfs(E, E);
for(i=1; i<N; i++) if(L[edge[i].u]>L[edge[i].v]) swap(edge[i].u, edge[i].v);
decomp(1, 0, 0);
while(Q--)
{
int A, B;
scanf("%d%d", &A, &B);
if(reach(A, E, B)) { printf("escaped\n"); continue; }
ll t=query(B, A);
if(t==INF) printf("oo\n");
else printf("%lld\n", t);
}
}
