#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ii = pair<int, int>;
using vi = vector<int>;
using vl = vector<ll>;
#define dbg(x) cerr << #x << " = " << (x) << endl;
#define raya cerr << " ==================== " << endl;
#define rep(i, a, b) for (auto i = a; i < (b); ++i)
#define sz(x) (int)(x).size()
#define all(x) begin(x), end(x)
int n, s, q, e, lim = 17;
ll inf = ll(1e16);
using par = pair<int,ll>;
vector<vector<par>> adj;
vector<bool> vis, ist;
vi inp, out, niv;
vl dist, mag;
vector<vector<par>> miele;
void gaaa(int u, int& t, int p, ll d, int lev) {
inp[u] = t;
miele[0][u] = {p, 0};
niv[u] = lev;
dist[u] = d;
for(auto& [v, w]: adj[u]) {
if (inp[v] >= 0) continue;
gaaa(v, ++t, u, d+w, lev+1);
}
out[u] = t++;
}
bool anc(int u, int v) {
return inp[u] <= inp[v] and out[v] <= out[u];
}
ll magico(int u) {
vis[u] = 1;
for(auto& [v,w]: adj[u]) {
if (vis[v])continue;
mag[u] = min(mag[u], magico(v) + 2*w);
}
if (ist[u]) mag[u] = -dist[u];
return mag[u];
}
void here() {
for (auto i = 0; i < n; i++) {
auto [p, m] = miele[0][i];
//miele[0][i].second = min(mag[i], mag[p]);
miele[0][i].second = mag[p];
}
for (auto i = 1; i < lim; i++) {
for (auto j = 0; j < n; j++) {
miele[i][j] = { miele[i-1][miele[i-1][j].first].first,
min(miele[i-1][j].second, miele[i-1][miele[i-1][j].first].second)
};
}
}
}
int main() {
cin.tie(0)->sync_with_stdio(0);
cin.exceptions(cin.failbit);
cin >> n >> s >> q >> e;
vector<ii> edg(n);
--e;
adj.assign(n, vector<par>());
ist.assign(n,0);
vis.assign(n,0);
inp.assign(n, -1);
out.assign(n, 0);
niv.assign(n, 0);
dist.assign(n, 0);
mag.assign(n, inf);
miele.assign(lim, vector<par>(n));
for (auto i = 0; i < n-1; i++) {
int x,y; ll w; cin >> x >> y >> w;
--x,--y;
edg[i]={x,y};
adj[x].emplace_back(y, w);
adj[y].emplace_back(x, w);
}
for (auto i = 0; i < s; i++) {int x; cin >> x; ist[x-1]=1;}
int xd = 0;
gaaa(e, xd, e, 0, 0);
magico(e);
here();
adj.clear();
for (auto q_ = 0; q_ < q; q_++) {
int x, y; cin >> x >> y;
--x, --y;
int p =(inp[edg[x].first]> inp[edg[x].second])?edg[x].first:edg[x].second;
if (anc(p, y)) {
int d = niv[y] - niv[p];
ll m = mag[y];
xd = y;
for (auto i = 0; i < lim; i++)
if (d & 1<<i)
m = min(m, miele[i][y].second), y = miele[i][y].first;
if (m == inf) cout << "oo\n";
else cout << m + dist[xd]<<'\n';
} else {
cout << "escaped\n";
}
}
//for(auto& i: mag) cout <<i<<' '; cout << '\n';
//for(auto& [v,w]: miele[0]) cout << v<<'.'<<w<<' ';cout <<'\n';
}
