#include <bits/stdc++.h>
#define task "1"
#define ll long long
#define double long double
#define ii pair<int, int>
#define li pair<ll, int>
#define fi first
#define se second
#define all(v) (v).begin(), (v).end()
#define FULL(i) ((1LL << i) - 1)
#define MASK(i) (1LL << i)
#define c_bit(i) __builtin_popcountll(i)
#define Bit(mask, i) ((mask >> i) & 1)
#define onbit(mask, i) ((mask) bitor (1LL << i))
#define offbit(mask, i) ((mask) &~ (1LL << i))
using namespace std;
const int maxn = 1e5 + 5;
const ll oo = 1e16;
const int mod = 1e9 + 7;
const int dx[] = {0, 1, 0, -1} , dy[] = {1, 0, -1, 0};
template <class X, class Y> bool maximize(X &a, const Y &b)
{
if(a < b) return a = b, true;
return false;
}
template <class X, class Y> bool minimize(X &a, const Y &b)
{
if(a > b) return a = b, true;
return false;
}
int n, s, q, h, in[maxn], out[maxn], depth[maxn], pos[maxn]; ll res[maxn], t[maxn << 2]; bool shop[maxn];
vector<ii> adj[maxn], queries[maxn]; ll d[maxn], lazy[maxn << 2]; ii rmq[maxn << 1][20], edges[maxn];
void dfs(int u, int p)
{
static int timeDfs = 0, id = 0;
in[u] = ++ timeDfs;
rmq[++ id][0] = {depth[u], u};
pos[u] = id;
for(auto [v, w] : adj[u]) if(v != p){
depth[v] = depth[u] + 1;
d[v] = d[u] + w;
dfs(v, u);
rmq[++ id][0] = {depth[u], u};
}
out[u] = timeDfs;
}
bool inSubTree(int v, int u) { return in[u] <= in[v] && in[v] <= out[u]; }
ll dist(int u, int v)
{
int l = pos[u], r = pos[v];
if(l > r) swap(l, r);
int h = __lg(r - l + 1);
int lca = min(rmq[l][h], rmq[r - (1 << h) + 1][h]).se;
return d[u] + d[v] - 2 * d[lca];
}
void down(int id)
{
if(!lazy[id]) return;
for(int i : {id << 1, id << 1 | 1}){
t[i] += lazy[id];
lazy[i] += lazy[id];
}
lazy[id] = 0;
}
void update(int u, int v, ll val, int id = 1, int l = 1, int r = n)
{
if(r < u || l > v) return;
if(u <= l && r <= v){
t[id] += val;
lazy[id] += val;
return;
}
down(id);
int mid = l + r >> 1;
update(u, v, val, id << 1, l, mid);
update(u, v, val, id << 1 | 1, mid + 1, r);
t[id] = min(t[id << 1], t[id << 1 | 1]);
}
ll get(int u, int v, int id = 1, int l = 1, int r = n)
{
if(r < u || l > v) return oo;
if(u <= l && r <= v) return t[id];
down(id);
int mid = l + r >> 1;
return min(get(u, v, id << 1, l, mid), get(u, v, id << 1 | 1, mid + 1, r));
}
void solve(int u, int p)
{
for(auto [e, i] : queries[u]){
auto [x, y] = edges[e];
if(depth[x] < depth[y]) swap(x, y);
if(!inSubTree(u, x)) { res[i] = -1; continue; }
res[i] = get(in[x], out[x]);
}
for(auto [v, w] : adj[u]) if(v != p){
update(in[v], out[v], -w);
update(1, in[v] - 1, w);
update(out[v] + 1, n, w);
solve(v, u);
update(in[v], out[v], w);
update(1, in[v] - 1, -w);
update(out[v] + 1, n, -w);
}
}
int main()
{
ios_base::sync_with_stdio(false); cin.tie(nullptr);
if(fopen(task".inp", "r")){
freopen(task".inp", "r", stdin);
freopen(task".out", "w", stdout);
}
cin >> n >> s >> q >> h;
for(int i = 1; i < n; ++ i){
int u, v, w; cin >> u >> v >> w;
edges[i] = {u, v};
adj[u].push_back({v, w});
adj[v].push_back({u, w});
}
dfs(h, 0);
for(int k = 1; 1 << k <= n << 1; ++ k) for(int i = 1; i + (1 << k) - 1 <= n << 1; ++ i)
rmq[i][k] = min(rmq[i][k - 1], rmq[i + (1 << k - 1)][k - 1]);
for(int i = 1; i <= s; ++ i){
int u; cin >> u;
shop[u] = true;
update(in[u], in[u], dist(u, h));
}
for(int u = 1; u <= n; ++ u) if(!shop[u]) update(in[u], in[u], oo);
for(int i = 1; i <= q; ++ i){
int e, u; cin >> e >> u;
queries[u].push_back({e, i});
}
solve(h, 0);
for(int i = 1; i <= q; ++ i){
if(!~res[i]) cout << "escaped\n";
else if(res[i] > 1e14) cout << "oo\n";
else cout << res[i] << '\n';
}
return 0;
}
