#include <bits/stdc++.h>
#define ll long long
#define endl "\n"
using namespace std;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
const ll N = 1e5 + 5;
ll st[N << 2];
void build(ll l, ll r, ll v)
{
if (l == r)
{
st[v] = 1e18;
return;
}
ll mid = (l + r) >> 1;
build(l, mid, v << 1);
build(mid + 1, r, v << 1 | 1);
st[v] = 1e18;
}
void modify(ll i, ll j, ll x, ll l, ll r, ll v)
{
if (max(i, l) > min(j, r))
return;
if (i <= l and r <= j)
{
st[v] = min(st[v], x);
return;
}
ll mid = (l + r) >> 1;
modify(i, j, x, l, mid, v << 1);
modify(i, j, x, mid + 1, r, v << 1 | 1);
}
ll query(ll i, ll l, ll r, ll v)
{
if (l == r)
return st[v];
ll mid = (l + r) >> 1;
if (i <= mid)
return min(st[v], query(i, l, mid, v << 1));
else
return min(st[v], query(i, mid + 1, r, v << 1 | 1));
}
vector<pair<ll, ll>> g[N];
ll mn[N], d[N], f[N], timer, p[N], ans[N];
pair<ll, ll> e[N];
vector<pair<ll, ll>> qs[N];
ll n, s, q, root, depth[N];
void init(ll v, ll par = 0)
{
d[v] = ++timer;
p[v] = par;
for (auto [to, w] : g[v])
if (to != par)
{
depth[to] = depth[v] + w;
init(to, v);
mn[v] = min(mn[v], mn[to] + w);
}
f[v] = timer;
}
void dfs(ll v, ll par = 0)
{
for (auto [to, w] : g[v])
if (to != par)
dfs(to, v);
modify(d[v], f[v], mn[v] - depth[v], 1, n, 1);
for (auto [r, ind] : qs[v])
if (!(d[v] <= d[r] and d[r] <= f[v])) ans[ind] = -1;
else ans[ind] = query(d[r], 1, n, 1) + depth[r];
}
void solve()
{
cin >> n >> s >> q >> root;
for (ll i = 1; i <= n; i++)
mn[i] = 1e18;
for (ll i = 1; i < n; i++)
{
ll a, b, c;
cin >> a >> b >> c;
g[a].push_back(make_pair(b, c));
g[b].push_back(make_pair(a, c));
e[i] = make_pair(a, b);
}
while (s--)
{
ll x;
cin >> x;
mn[x] = 0;
}
init(root);
for (ll i = 1; i < n; i++)
if (p[e[i].first] != e[i].second)
swap(e[i].first, e[i].second);
build(1, n, 1);
for (ll i = 0; i < q; i++)
{
ll x, y;
cin >> x >> y;
qs[e[x].first].push_back(make_pair(y, i));
}
dfs(root);
for (ll i = 0; i < q; i++) if (ans[i] == -1) cout << "escaped\n";
else if (ans[i] >= 1e18) cout << "oo\n";
else cout << ans[i] << endl;
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
ll t = 1;
// precomp();
// cin >> t;
for (ll cs = 1; cs <= t; cs++)
solve();
// cerr << "\nTime elapsed: " << clock() * 1000.0 / CLOCKS_PER_SEC << " ms\n";
}
