#include <bits/stdc++.h>
using namespace std;
// #undef _GLIBCXX_DEBUG // disable run-time bound checking, etc
// #pragma GCC optimize("Ofast,inline") // Ofast = O3,fast-math,allow-store-data-races,no-protect-parens
// #pragma GCC optimize ("unroll-loops")
// #pragma GCC target("bmi,bmi2,lzcnt,popcnt") // bit manipulation
// #pragma GCC target("movbe") // byte swap
// #pragma GCC target("aes,pclmul,rdrnd") // encryption
// #pragma GCC target("avx,avx2,f16c,fma,sse3,ssse3,sse4.1,sse4.2") // SIMD
// #include <bits/extc++.h>
// using namespace __gnu_pbds;
// template<class T>using ordered_set = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;
// template<class T>using ordered_multiset = tree<T, null_type, less_equal<T>, rb_tree_tag,tree_order_statistics_node_update>;
#define ll long long
#define INF (ll)1e9+7
#define fo(i, n) for(int i=0;i<((ll)n);i++)
#define deb(x) cout << #x << " = " << x << endl;
#define deb2(x, y) cout << #x << " = " << x << ", " << #y << " = " << y << endl
#define pb push_back
#define mp make_pair
#define F first
#define S second
#define LSOne(S) ((S) & (-S))
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
inline int readint(){ int v = 0; char c; while((c = getchar()) != EOF && c != ' ' && c != '\n'){ v *= 10; v += c - '0'; } return v; }
inline int readintsigned() { int v = 0; int sign = 1; char c = getchar(); if (c == '-') { sign = -1; } else { v += c - '0'; } while ((c = getchar()) != EOF && c != ' ' && c != '\n') { v *= 10; v += c - '0'; } return v * sign; }
inline string readstring() { string s; char c; while ((c = getchar()) != EOF && c != '\n' && c != ' ') { s.push_back(c); } return s; }
template <class result_t=std::chrono::milliseconds,class clock_t=std::chrono::steady_clock,class duration_t = std::chrono::milliseconds>
auto since(std::chrono::time_point<clock_t, duration_t> const& start){return std::chrono::duration_cast<result_t>(clock_t::now() - start);}
typedef pair<int, int> pii;
typedef pair<ll, ll> pl;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<pii> vpii;
typedef vector<pl> vpl;
typedef vector<vi> vvi;
typedef vector<vl> vvl;
typedef vector<vpii> vvpii;
typedef vector<vpl> vvpl;
vl toStore;
vvpl adj(100001);
vpl paths;
vl closestShop(100001, 1e18);
vvl bl(100001, vl(24, -1));
vl v(100001);
int sIndex = 0;
ll lengthTo[100001];
int depth[100001];
int siz[100001];
int segIndex[100001];
int heavyChild[100001];
int heavyParent[100001];
int dfs(int u, int d, int last){ // siz, toShop
bl[u][0] = last;
depth[u] = d;
siz[u] = 1;
int t_heavyestChild = -1;
for(auto &[v, w] : adj[u]){
if(v == last) continue;
siz[u] += dfs(v, d+1, u);
closestShop[u] = min(closestShop[u], closestShop[v]+w);
if(siz[v] > t_heavyestChild){
t_heavyestChild = siz[v];
heavyChild[u] = v;
}
}
return siz[u];
}
void dfs2(int u, int last = -1, int heavyPar = -1){
if(heavyPar == -1) heavyPar = u;
heavyParent[u] = heavyPar;
v[sIndex] = closestShop[u];
segIndex[u] = sIndex++;
if(heavyChild[u] != -1) dfs2(heavyChild[u], u, heavyPar);
for(auto &[v, w] : adj[u]){
if(v == last || heavyChild[u] == v) continue;
dfs2(v, u);
}
}
void dfs3(int u, int last = -1, ll dis = 0){
lengthTo[segIndex[u]] = dis;
for(auto &[v, w] : adj[u]){
if(v == last) continue;
dfs3(v, u, dis-w);
}
}
struct Node{
Node *lnode, *rnode;
int l, r;
ll val;
Node(int l, int r) : l(l), r(r){
if(r-l == 1) {
val = v[l]+lengthTo[l];
}
else{
int mid = (l + r) / 2;
lnode = new Node(l, mid);
rnode = new Node(mid, r);
val = min(lnode->val, rnode->val);
}
}
ll query(int lo, int hi){
if(hi <= l || r <= lo) return 1e18;
if(lo <= l && r <= hi) return val;
return min(lnode->query(lo, hi), rnode->query(lo, hi));
}
};
int main() {
// cout << fixed << setprecision(20);
// auto start = std::chrono::steady_clock::now(); // since(start).count()
cin.tie(0)->sync_with_stdio(0);
ll n, s, q, e, from, to, val, closed, start;
cin >> n >> s >> q >> e;
fo(i, n-1){
cin >> from >> to >> val;
adj[--from].pb({--to, val});
adj[to].pb({from, val});
paths.pb({from, to});
}
fo(i, s){
cin >> val;
closestShop[val-1] = 0;
}
memset(depth, 0, sizeof(depth));
memset(siz, 0, sizeof(siz));
memset(segIndex, 0, sizeof(segIndex));
memset(heavyChild, -1, sizeof(heavyChild));
memset(heavyParent, 0, sizeof(heavyParent));
memset(lengthTo, 0, sizeof(lengthTo));
e--;
dfs(e, 0, e);
dfs2(e);
dfs3(e);
fo(i, 22){
fo(j, n)
bl[j][i+1] = bl[bl[j][i]][i];
}
Node st(0, n);
fo(x, q){
cin >> closed >> start;
pl path = paths[closed-1];
start--;
int closedNode = (depth[path.F] < depth[path.S] ? path.S : path.F);
if(depth[start] >= depth[closedNode]){
int tempNode = start;
for(int mask = depth[start]-depth[closedNode];mask;mask-=LSOne(mask)){
tempNode = bl[tempNode][__builtin_ctz(LSOne(mask))];
}
if(tempNode == closedNode){
tempNode = start;
ll res = 1e18;
while(depth[tempNode] >= depth[closedNode]){
int nextNode = heavyParent[tempNode];
res = min(res, st.query(segIndex[nextNode]+max(0, depth[closedNode]-depth[nextNode]), segIndex[tempNode]+1));
if(depth[tempNode] == 0) break;
tempNode = bl[nextNode][0];
}
res -= lengthTo[segIndex[start]];
cout << (res>1e17?"oo":to_string(res)) << "\n";
continue;
}
}
cout << "escaped\n";
}
return 0;
}
