#include <bits/stdc++.h>
#define ll long long
#define pii pair<int, int>
using namespace std;
const ll oo = 1e18;
const int MAX = 1e5 + 5;
const int LOGMAX = 17;
struct edge{
int a, b, w;
};
edge edges[MAX];
vector<int> g[MAX];
bool shop[MAX];
ll dp[MAX];
array<ll, 3> par[LOGMAX][MAX];
int t = 0;
int timeIn[MAX], timeOut[MAX];
void dfs1(int node, int p){
par[0][node] = {p, 0, 0};
dp[node] = oo;
if(shop[node]) dp[node] = 0;
timeIn[node] = ++t;
for(int i:g[node]){
edge& e = edges[i];
if(e.a != node){
swap(e.a, e.b);
}
if(e.b == p){
swap(e.a, e.b);
continue;
}
dfs1(e.b, node);
par[0][e.b][1] = e.w;
dp[node] = min(dp[node], dp[e.b] + e.w);
}
par[0][node][2] = dp[node];
timeOut[node] = ++t;
}
bool isAncestor(int a, int b){
return timeIn[a] <= timeIn[b] && timeOut[a] >= timeOut[b];
}
ll lift(int node, int p){
ll ans = oo;
ll d = 0;
for (int j = LOGMAX - 1; j >= 0; --j)
{
int a = par[j][node][0];
if(isAncestor(a, p)) continue;
ans = min(ans, par[j][node][2] + d);
d += par[j][node][1];
node = a;
}
ans = min(ans, par[0][node][2] + d);
return ans;
}
int n, s, q, r;
int main()
{
cin >> n >> s >> q >> r;
for (int i = 1; i <= n - 1; i++)
{
edge e;
cin >> e.a >> e.b >> e.w;
edges[i] = e;
g[e.a].push_back(i);
g[e.b].push_back(i);
}
for (int i = 0; i < s; i++)
{
int a; cin >> a;
shop[a] = 1;
}
dfs1(r, r);
for (int j = 1; j < LOGMAX; j++)
{
for (int i = 1; i <= n; i++)
{
int m = par[j - 1][i][0];
par[j][i][0] = par[j - 1][m][0];
par[j][i][1] = par[j - 1][i][1] + par[j - 1][m][1];
par[j][i][2] = min(par[j - 1][i][2], par[j - 1][i][1] + par[j - 1][m][2]);
}
}
while(q--){
int a, b; cin >> a >> b;
if(!isAncestor(edges[a].b, b)){
cout << "escaped\n";
continue;
}
ll ans = lift(b, edges[a].a);
if(ans == oo){
cout << "oo\n";
}
else{
cout << ans << '\n';
}
}
}
