#include <bits/stdc++.h>
using namespace std;
using ll = long long int;
const int sn = 1e5+7;
ll i, j, di, n, s, q, e, t1, t2, ww, va, le[sn], ri[sn], dis[sn], cur, pap[18][sn]; bool sh[sn];
ll mid[sn], qee[sn];
array<ll, 3> tem;
array<ll, 2> tem2;
vector<array<ll, 3>> v[sn];
vector<array<ll, 2>> qe[sn];
void dfs(ll cu, ll pa){
for(array<ll, 3> z: v[cu]){
if(z[0] != pa){
dfs(z[0], cu);
mid[cu] = min(mid[cu], mid[z[0]]+z[1]);
// cout << z[0] << ' ';
}
} // cout << '\n';
// cout << cu << ' ' << mid[cu] << '\n';
}
void dfs2(ll cu, ll pa){
dis[cu] = di; mid[cu] -= di;
// cout << cu << ' ' << dis[cu] << ' ' << mid[cu] << '\n';
for(array<ll, 3> z: v[cu]){
if(z[0] != pa){
di += z[1];
dfs2(z[0], cu);
di -= z[1];
}
}
}
void dfs3(ll cu, ll pa){
for(array<ll, 3> z: v[cu]){
if(z[0] == pa) continue;
cur = cu;
for( j = 17; j >= 0; j--) if(mid[pap[j][cur]] >= mid[z[0]]) cur = pap[j][cur];
if(mid[cu] < mid[z[0]]) pap[0][z[0]] = cu;
else pap[0][z[0]] = pap[0][cur];
for( j = 1; j < 18; j++) pap[j][z[0]] = pap[j-1][pap[j-1][z[0]]];
dfs3(z[0], cu);
}
}
void dfs4(ll cu, ll pa){
for(array<ll, 2> z: qe[cu]){
// cout << cu << ' ' << z[0] << ' ' << z[1] << '\n';
if(!sh[z[0]]) qee[z[1]] = -1;
else{
di = max(dis[le[z[0]]], dis[ri[z[0]]]);
// cout << le[z[0]] << ' ' << ri[z[0]] << ' ' << di << ' ';
cur = cu;
for( j = 17; j >= 0; j--) if(dis[pap[j][cur]] >= di) cur = pap[j][cur];
// cout << cur << '\n';
qee[z[1]] = mid[cur]+dis[cu];
}
}
for(array<ll, 3> z: v[cu]){
if(z[0] == pa) continue;
sh[z[2]] = 1;
dfs4(z[0], cu);
sh[z[2]] = 0;
}
}
void run(){
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
// int tt; cin >> tt; while(tt--) run();
cin >> n >> s >> q >> e;
for( i = 1; i < n; i++){
cin >> t1 >> t2 >> ww;
le[i] = t1; ri[i] = t2;
tem[0] = t2;
tem[1] = ww;
tem[2] = i;
v[t1].push_back(tem);
tem[0] = t1;
v[t2].push_back(tem);
sh[i] = 0;
}
for( i = 1; i <= n; i++) mid[i] = 1e18;
for( i = 1; i <= s; i++) cin >> va, mid[va] = 0;
mid[e] = -1e18;
dfs(e, -1);
di = 0;
dfs2(e, -1);
for( i = 0; i < 18; i++) pap[i][e] = e;
dfs3(e, -1);
for( i = 0; i < q; i++){
cin >> t1 >> t2;
tem2[0] = t1; tem2[1] = i;
qe[t2].push_back(tem2);
}
dfs4(e, -1);
for( i = 0; i < q; i++){
if(qee[i] == -1) cout << "escaped\n";
else if(qee[i] >= 1e18) cout << "oo\n";
else cout << qee[i] << '\n';
}
}
