#include <bits/stdc++.h>
#define pii pair<int,int>
#define x first
#define y second
#define ll long long
using namespace std;
const int NMAX=1e5+7;
const int LogNMAX=25;
const ll INF=1e18;
int n,s,q,E,tin[NMAX],tout[NMAX],par[LogNMAX][NMAX],lvl[NMAX];
vector<pii> g[NMAX];
ll dp[NMAX], dep[NMAX], mn[LogNMAX][NMAX];
struct edge{int a,b,w;};
edge e[NMAX];
int Time=0;
void Dfs(int son, int p, ll D)
{
tin[son]=++Time;
par[0][son]=p;
dep[son]=D;
for(pii i:g[son])
{
if(i.x==p) continue;
lvl[i.x]=lvl[son]+1;
Dfs(i.x, son, D+1LL*i.y);
dp[son]=min(dp[son],dp[i.x]+1LL*i.y);
}
tout[son]=Time;
}
int ok(int A, int B)
{
return tin[B]<=tin[A] && tout[B]>=tout[A];
}
int main()
{
ios_base::sync_with_stdio(false);
cin>>n>>s>>q>>E;
for(int i=0;i<=n;i++) dp[i]=INF;
for(int i=1;i<=n-1;i++)
{
cin>>e[i].a>>e[i].b>>e[i].w;
g[e[i].a].push_back({e[i].b, e[i].w});
g[e[i].b].push_back({e[i].a, e[i].w});
}
while(s--)
{
int c; cin>>c;
dp[c]=0;
}
Dfs(E,0,0);
for(int i=1;i<=n;i++) if(par[0][e[i].a]==e[i].b) swap(e[i].a, e[i].b);
for(int i=1;i<=n;i++) mn[0][i]=dp[i]-dep[i];
for(int i=1;i<LogNMAX;i++) for(int j=1;j<=n;j++)
{
par[i][j]=par[i-1][par[i-1][j]];
mn[i][j]=min(mn[i-1][j], mn[i-1][par[i-1][j]]);
}
while(q--)
{
int idx,node; cin>>idx>>node;
idx=e[idx].b;
if(!ok(node,idx))
{
cout<<"escaped"<<endl;
continue;
}
ll res=INF;
int idi=lvl[node]-lvl[idx]+1;
int tmp=node;
for(int i=0;i<LogNMAX;i++)
{
if(idi&(1<<i))
{
res=min(res,mn[i][node]);
node=par[i][node];
}
}
res+=dep[tmp];
if(res>1e17+20) cout<<"oo"<<endl;
else cout<<res<<endl;
}
return 0;
}
