#include <bits/stdc++.h>
#define pb emplace_back
#define ll long long
#define fi first
#define se second
#define mp make_pair
using namespace std;
const int N = int(1e5) + 7;
const int logN = 17;
const ll inf = (ll)1e18;
typedef pair<int, int> pii;
ll f[N], res, g[N][logN + 1], dis[N][logN + 1];
pii e[N];
bool shop[N];
int n, s, u, v, w, del, r, q, root, T = 0;
int p[N][logN + 1], in[N], h[N], out[N];
vector<pii> a[N];
void DFS(int u) {
in[u] = ++T;
if(shop[u]) f[u] = 0;
else f[u] = inf;
for(int j = 1; j <= logN; ++j) {
p[u][j] = p[p[u][j - 1]][j - 1];
dis[u][j] = dis[u][j - 1] + dis[p[u][j - 1]][j - 1];
}
for(pii& lst: a[u]) {
int v = lst.fi, w = lst.se;
if(v == p[u][0]) continue;
p[v][0] = u, dis[v][0] = w;
h[v] = h[u] + 1;
DFS(v);
f[u] = min(f[u], f[v] + w);
}
g[u][0] = f[p[u][0]] + dis[u][0];
out[u] = T;
}
bool uIsParentOfv(int u, int v) {
return in[u] <= in[v] && out[v] <= out[u];
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0), cout.tie(0);
#define Task "test"
if(fopen(Task".inp", "r")) {
freopen(Task".inp", "r", stdin);
freopen(Task".out", "w", stdout);
}
cin >> n >> s >> q >> root;
for(int i = 1; i < n; ++i) {
cin >> u >> v >> w;
e[i] = mp(u, v);
a[u].pb(v, w), a[v].pb(u, w);
}
for(int i = 1; i <= s; ++i) cin >> u, shop[u] = 1;
DFS(root);
for(int j = 1; j <= logN; ++j) {
for(int i = 1; i <= n; ++i) {
g[i][j] = min(g[i][j - 1], g[p[i][j - 1]][j - 1] + dis[i][j - 1]);
}
}
while(q --) {
cin >> del >> r; /// cat canh del va dang o dinh r
u = e[del].fi, v = e[del].se;
if(uIsParentOfv(v, u)) swap(u, v); /// u is parent of v
if(uIsParentOfv(v, r)) {
res = f[r];
for(int i = logN; i >= 0; --i) {
if(h[r] - (1 << i) >= h[v]) {
res = min(res, g[r][i]);
r = p[r][i];
}
}
if(res >= inf) cout << "oo\n";
else cout << res << '\n';
} else cout << "escaped\n";
}
}
