#include <bits/stdc++.h>
using namespace std;
struct edge {
int u, v, w;
int other( int x ) {
return u ^ v ^ x;
}
};
struct query {
int v, e;
};
struct SegTree {
int l, r;
long long zero;
vector<long long> aint;
void init( int _l, int _r, long long _zero ) {
l = _l;
r = _r;
zero = _zero;
aint.resize( 4 * (r - l + 1) );
for ( int v = 0; v < aint.size(); v++ )
aint[v] = zero;
}
void update( int v, int l, int r, int p, long long x ) {
if ( l > p || r < p )
return;
if ( l == r ) {
aint[v] = x;
return;
}
int mid = (l + r) / 2;
update( v * 2 + 1, l, mid, p, x );
update( v * 2 + 2, mid + 1, r, p, x );
aint[v] = min( aint[v * 2 + 1], aint[v * 2 + 2] );
}
void update( int p, long long x ) {
update( 0, l, r, p, x );
}
long long query( int v, int l, int r, int lq, int rq ) {
if ( l > rq || r < lq )
return zero;
if ( lq <= l && r <= rq )
return aint[v];
int mid = (l + r) / 2;
return min( query( v * 2 + 1, l, mid, lq, rq ), query( v * 2 + 2, mid + 1, r, lq, rq ) );
}
long long query( int lq, int rq ) {
return query( 0, l, r, lq, rq );
}
};
const int MAX_N = 1e5;
const int MAX_Q = 1e5;
const long long INF = 1e15;
bool isShop[MAX_N + 1];
int pos[MAX_N + 1];
long long depth[MAX_N + 1], distShop[MAX_N + 1], ans[MAX_Q + 1];
edge edges[MAX_N];
query queries[MAX_Q];
vector<int> adj[MAX_N + 1], queriesByVert[MAX_N + 1];
SegTree minDist;
void calc( int u, int p ) {
distShop[u] = (isShop[u] ? 0 : INF);
for ( int e: adj[u] ) {
int v = edges[e].other( u ), w = edges[e].w;
if ( v == p )
continue;
depth[v] = depth[u] + w;
calc( v, u );
distShop[u] = min( distShop[u], distShop[v] + w );
}
}
void solve( int u, int p, int d ) {
minDist.update( d, distShop[u] - depth[u] );
pos[u] = d;
for ( int e: adj[u] ) {
int v = edges[e].other( u );
if ( v == p )
continue;
solve( v, u, d + 1 );
}
for ( int q: queriesByVert[u] ) {
int v = (depth[edges[queries[q].e].u] < depth[edges[queries[q].e].v] ? edges[queries[q].e].v : edges[queries[q].e].u);
if ( pos[v] == 0 )
ans[q] = -1;
else
ans[q] = minDist.query( pos[v], pos[u] ) + depth[u];
}
minDist.update( d, INF );
pos[u] = 0;
}
int main() {
int n, s, q, e;
cin >> n >> s >> q >> e;
for ( int i = 1; i <= n - 1; i++ ) {
cin >> edges[i].u >> edges[i].v >> edges[i].w;
adj[edges[i].u].push_back( i );
adj[edges[i].v].push_back( i );
}
for ( int i = 0; i < s; i++ ) {
int v;
cin >> v;
isShop[v] = true;
}
for ( int i = 0; i < q; i++ ) {
cin >> queries[i].e >> queries[i].v;
queriesByVert[queries[i].v].push_back( i );
}
minDist.init( 1, n, INF );
calc( e, 0 );
solve( e, 0, 1 );
for ( int i = 0; i < q; i++ ) {
if ( ans[i] == -1 )
cout << "escaped\n";
else if ( ans[i] == INF )
cout << "oo\n";
else
cout << ans[i] << "\n";
}
return 0;
}
