/**
* user: ppavic
* fname: Patrik
* lname: Pavić
* task: valley
* score: 100.0
* date: 2019-05-04 08:02:52.599602
*/
#include <cstdio>
#include <cstring>
#include <vector>
#include <algorithm>
#define X first
#define Y second
#define PB push_back
using namespace std;
typedef long long ll;
typedef pair < int, ll > pil;
const int N = 1e5 + 500;
const int LOG = 18;
const ll INF = 0x3f3f3f3f;
int par[N][LOG], ind[N], dep[N], A[N], B[N];
ll dis[N][LOG], dp2[N][LOG], dp[N];
int n, E, m, q;
vector < pil > v[N];
vector < ll > dp3[N], dp3_r[N];
ll f(int x,int lst){
par[x][0] = lst; dp2[x][0] = INF * INF; dep[x] = dep[lst] + 1;
ll cur = INF * INF;int koj = 0;
for(pil y : v[x]){
dp3[x].PB(dp[x]);
if(y.X == lst) continue;
ind[y.X] = koj++;
dis[y.X][0] = y.Y;
f(y.X, x);
dp[x] = min(dp[x], dp[y.X] + y.Y);
}
reverse(v[x].begin(), v[x].end());
for(pil y : v[x]){
dp3_r[x].PB(dp[x]);
if(y.X == lst) continue;
cur = min(cur, dp[y.X] + y.Y);
}
reverse(dp3_r[x].begin(), dp3_r[x].end());
}
void napravi_sve_bitno(){
// jos treba postaviti dp2[i][0] na sam parenta -- jesam
for(int i = 1;i <= n;i++){
dp2[i][0] = dis[i][0] + min(dp3[par[i][0]][ind[i]], dp3_r[par[i][0]][ind[i]]);
}
for(int k = 1;k < LOG;k++){
for(int i = 1;i <= n;i++){
par[i][k] = par[par[i][k - 1]][k - 1];
dis[i][k] = dis[i][k - 1] + dis[par[i][k - 1]][k - 1];
dp2[i][k] = min(dp2[i][k - 1], dis[i][k - 1] + dp2[par[i][k - 1]][k - 1]);
//dp2[i][k] = min(dp2[i][k], min(dp3[par[par[i][k - 1]][0]][ind[par[i][k - 1]]], dp3_r[par[par[i][k - 1]][0]][ind[par[i][k - 1]]])); -- mislim da ovo ne treba
}
}
}
bool nalazi(int x,int y){
if(dep[y] > dep[x]) return 0;
for(int i = LOG - 1;i >= 0;i--){
if(dep[x] - (1 << i) >= dep[y])
x = par[x][i];
}
return x == y;
}
ll nadi(int x,int y){
ll ret = dp[x], cur_d = 0;
//printf("NADI %d i %d DP %lld\n", x, y, dp[x]);
for(int i = LOG - 1;i >= 0;i--){
if(dep[x] - (1 << i) >= dep[y]){
ret = min(ret, cur_d + dp2[x][i]);
cur_d += dis[x][i];
x = par[x][i];
}
}
return ret;
}
int main(){
scanf("%d%d%d%d", &n, &m, &q, &E);
for(int i = 1;i < n;i++){
int x, y, z; scanf("%d%d%d", &x, &y, &z);
v[x].PB({y, z});
v[y].PB({x, z});
A[i] = x, B[i] = y;
dp[i] = INF * INF;
}
dp[n] = INF * INF;
for(int i = 0;i < m;i++){
int x; scanf("%d", &x); dp[x] = 0;
}
f(E, E);
//return 0;
napravi_sve_bitno();
for(int i = 0;i < q;i++){
int x, y; scanf("%d%d", &x, &y);
if(dep[A[x]] < dep[B[x]]) swap(A[x], B[x]);
if(!nalazi(y, A[x]) || !nalazi(y, B[x])){
printf("escaped\n"); continue;
}
ll ans = nadi(y, A[x]);
if(ans >= INF * INF) printf("oo\n");
else printf("%lld\n", ans);
}
}
