#include <bits/stdc++.h>
#define ll long long
#define s second
#define f first
#define pb push_back
#define pii pair <int,int>
#define left (h<<1),l,(l + r)/2
#define right ((h<<1)|1),(l + r)/2 + 1,r
#define int ll
using namespace std;
const int N = 1e5 + 3;
pair <pii,int> edge[N];
vector <pii> v[N];
int d[25][N],dep[N],dp[N],dist[N];
int mn[25][N];
int timer,tin[N],tout[N];
void dfs(int x,int par){
dep[x] = dep[par] + 1;
d[0][x] = par;
tin[x] = ++timer;
for (auto [to,w]: v[x]){
if (to==par) continue;
dp[to] = dp[x] + w;
dfs(to,x);
dist[x] = min(dist[x],dist[to] + w);
}
tout[x] = timer;
}
signed main(){
ios_base::sync_with_stdio(0),cin.tie(NULL),cout.tie(NULL);
int n,s,q,root;
cin>>n>>s>>q>>root;
for (int i = 1; i < n; i++){
int a,b,c;
cin>>a>>b>>c;
v[a].pb({b,c});
v[b].pb({a,c});
edge[i] = {{a,b},c};
}
for (int i = 1; i <= n; i++){
dist[i] = 1e18;
}
for (int i = 1; i <= s; i++){
int x;
cin>>x;
dist[x]=0;
}
dfs(root,root);
for (int i = 1; i < n; i++){
if (dep[edge[i].f.f] > dep[edge[i].f.s])
swap(edge[i].f.f,edge[i].f.s);
}
for (int i =0;i <= 18; i++)
for (int j = 0; j <= n; j++)
mn[i][j] = 1e18;
for (int j = 1; j <= n; j++)
mn[0][j] = dist[j];
for (int i = 1; i <= 18; i++){
for (int j = 1; j <= n; j++){
d[i][j] = d[i - 1][d[i - 1][j]];
mn[i][j] = min(mn[i - 1][j],dp[j] - dp[d[i - 1][j]] + mn[i - 1][d[i - 1][j]]);
}
}
while (q--){
int x,y;
cin>>x>>y;
x = edge[x].f.s;
if (!(tin[x] <= tin[y] && tout[y] <= tout[x])){
cout<<"escaped"<<endl;
continue;
}
int ans = 1e18,len = dep[y] - dep[x] + 1,D = 0;
for (int i = 18; i >= 0; i--){
if ((len & (1LL<<i)) > 0) {
ans = min(ans,mn[i][y] + D);
D += dp[y] - dp[d[i][y]];
y = d[i][y];
}
}
if (ans == 1e18) cout<<"oo"<<endl;
else cout<<ans<<endl;
}
}
