#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define sp ' '
#define en '\n'
#define smin(a, b) a = min(a, b)
#define smax(a, b) a = max(a, b)
using namespace std;
const int N = 1e5 + 2;
const int mod = 1e9 + 7;
const ll linf = 1e18;
int par[N][17];
ll mn[N][17];
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int n, s, q, e;
cin >> n >> s >> q >> e;
e -= 1;
vector<int> u(n), v(n), w(n);
vector<vector<array<int, 2>>> g(n);
for (int i = 0; i < n - 1; i++) {
cin >> u[i] >> v[i] >> w[i];
u[i] -= 1; v[i] -= 1;
g[u[i]].push_back({v[i], i});
g[v[i]].push_back({u[i], i});
}
vector<bool> is(n);
for (int i = 0; i < s; i++) {
int x; cin >> x; x -= 1;
is[x] = 1;
}
vector<int> in(n), out(n), dep(n);
int tsz = -1;
vector<ll> opt(n, linf), pref(n);
function<void(int, int, ll)> Dfs = [&] (int s, int e, ll o) {
in[s] = ++tsz;
pref[s] = o;
par[s][0] = e;
for (int i = 1; i < 17; i++) {
if (par[s][i - 1] != -1) par[s][i] = par[par[s][i - 1]][i - 1];
else par[s][i] = -1;
}
for (auto u : g[s]) {
if (u[0] == e) continue;
dep[u[0]] = dep[s] + 1;
Dfs(u[0], s, o + w[u[1]]);
smin(opt[s], opt[u[0]] + w[u[1]]);
}
if (is[s] == 1) opt[s] = 0;
out[s] = tsz;
};
Dfs(e, -1, 0);
for (int i = 0; i < n - 1; i++) {
if (in[u[i]] > in[v[i]]) swap(u[i], v[i]);
}
for (int i = 0; i < n; i++) {
if (opt[i] != linf) opt[i] -= pref[i];
}
function<void(int, int)> Dfs1 = [&] (int s, int e) {
mn[s][0] = opt[s];
for (int i = 1; i < 17; i++) {
mn[s][i] = mn[s][i - 1];
if (par[s][i - 1] != -1) smin(mn[s][i], mn[par[s][i - 1]][i - 1]);
}
for (auto u : g[s]) {
if (u[0] == e) continue;
Dfs1(u[0], s);
}
};
Dfs1(e, -1);
auto Get = [&] (int l, int r) {
int kol = dep[r] - dep[l];
ll ans = linf;
for (int i = 16; i >= 0; i--) {
if ((1 << i) & kol) {
smin(ans, mn[r][i]);
r = par[r][i];
}
}
return min(opt[l], ans);
};
while (q--) {
int x, y;
cin >> x >> y;
x -= 1; y -= 1;
if (!(in[v[x]] <= in[y] && out[y] <= out[v[x]])) {
cout << "escaped" << en;
continue;
}
if (opt[v[x]] == linf) {
cout << "oo" << en;
continue;
}
ll ans = pref[y] + Get(v[x], y);
cout << ans << en;
}
return 0;
}
