#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define all(a) (a).begin(), (a).end()
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef long double ld;
template<typename T1, typename T2> bool chkmin(T1 &x, T2 y) { return y < x ? (x = y, true) : false; }
template<typename T1, typename T2> bool chkmax(T1 &x, T2 y) { return y > x ? (x = y, true) : false; }
void debug_out()
{
cerr << endl;
}
template<typename T1, typename... T2> void debug_out(T1 A, T2... B)
{
cerr << ' ' << A;
debug_out(B...);
}
#ifdef DEBUG
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif
const int maxN = 100005;
const ll INF64 = 1e18;
int N, S, Q, root;
vector< pair<int, ll> > G[maxN];
bool good[maxN];
int par[maxN];
ll H[maxN];
int tin[maxN], tout[maxN];
ll ans[maxN];
vector<pii> qvtx[maxN];
int timer;
void dfs0(int v, int p = -1)
{
par[v] = p;
tin[v] = timer++;
for (auto e : G[v])
{
int u = e.fi;
ll c = e.se;
if (u != p)
{
H[u] = H[v] + c;
dfs0(u, v);
}
}
tout[v] = timer - 1;
}
bool upper(int a, int b)
{
return tin[a] <= tin[b] && tout[b] <= tout[a];
}
namespace sgt
{
ll t[4 * maxN];
void init()
{
fill(t, t + 4 * maxN, INF64);
}
void push(int v, int vl, int vr)
{
if (vl != vr)
{
chkmin(t[v << 1], t[v]);
chkmin(t[v << 1 | 1], t[v]);
}
}
void umin(int v, int vl, int vr, int l, int r, ll x)
{
if (l > r || vr < l || r < vl) return;
if (l <= vl && vr <= r)
{
chkmin(t[v], x);
return;
}
int vm = (vl + vr) >> 1;
push(v, vl, vr);
umin(v << 1, vl, vm, l, r, x);
umin(v << 1 | 1, vm + 1, vr, l, r, x);
}
ll gt(int v, int vl, int vr, int pos)
{
if (vl == vr)
{
return t[v];
}
int vm = (vl + vr) >> 1;
push(v, vl, vr);
if (pos <= vm)
return gt(v << 1, vl, vm, pos);
else
return gt(v << 1 | 1, vm + 1, vr, pos);
}
}
void umin(int l, int r, ll x)
{
sgt::umin(1, 0, N - 1, l, r, x);
}
ll gt(int pos)
{
return sgt::gt(1, 0, N - 1, pos);
}
ll dfs1(int v, int p = -1)
{
ll cd = INF64;
if (good[v])
{
umin(tin[v], tin[v], -H[v]);
cd = 0;
}
for (auto e : G[v])
{
int u = e.fi;
ll c = e.se;
if (u != p)
{
ll cd2 = dfs1(u, v) + c;
umin(tin[v], tin[u] - 1, -H[v] + cd2);
umin(tin[u], tout[u], -H[v] + cd);
chkmin(cd, cd2);
}
}
for (pii q : qvtx[v])
{
int u = q.fi;
int idx = q.se;
ans[idx] = gt(tin[u]) + H[u];
}
return cd;
}
signed main()
{
#ifdef DEBUG
freopen("in", "r", stdin);
#endif
ios::sync_with_stdio(0);
cin.tie(0);
cin >> N >> S >> Q >> root;
pii edges[N - 1];
for (int i = 0; i < N - 1; ++i)
{
int a, b;
long long c;
cin >> a >> b >> c;
G[a].emplace_back(b, c);
G[b].emplace_back(a, c);
edges[i] = {a, b};
}
while (S--)
{
int v;
cin >> v;
good[v] = true;
}
dfs0(root);
fill(ans, ans + Q, INF64);
for (int i = 0; i < Q; ++i)
{
int ei, u;
cin >> ei >> u;
--ei;
int v = edges[ei].fi == par[edges[ei].se] ? edges[ei].se : edges[ei].fi;
if (!upper(v, u))
{
ans[i] = -1;
continue;
}
qvtx[v].emplace_back(u, i);
}
sgt::init();
dfs1(root);
for (int i = 0; i < Q; ++i)
{
if (ans[i] == -1)
{
cout << "escaped\n";
}
else if (ans[i] >= INF64)
{
cout << "oo\n";
}
else
{
cout << (long long)ans[i] << '\n';
}
}
return 0;
}
