#include<bits/stdc++.h>
using namespace std;
long long n , s , q , e , dp [100005] , pr [100005] , st [100005][23] , sum [100005] , stt [100005][23];
vector < pair < int , int > > gr [100005] , edg;
void go ( int x , int p )
{
dp [x] = dp [p] + 1;
st [x][0] = p;
for ( auto xx : gr [x] )
{
int u = xx . first;
if ( u == p ) continue;
sum [u] = sum [x] + xx . second;
go ( u , x );
stt [x][0] = min ( stt [x][0] , stt [u][0] + xx . second );
}
}
int lca ( int x , int y )
{
if ( dp [x] > dp [y] ) swap ( x , y );
int dif = dp [y] - dp [x];
for ( int i = 0 ; i < 21 ; i ++ )
{
if ( ( dif & ( 1 << i ) ) ) y = st [y][i];
}
if ( x == y ) return x;
for ( int i = 21 ; i >= 0 ; i -- )
{
if ( st [x][i] != st [y][i] )
{
x = st [x][i];
y = st [y][i];
}
}
return st [x][0];
}
int main()
{
cin >> n >> s >> q >> e;
for ( int i = 0 ; i < n - 1 ; i ++ )
{
int x , y , z;
cin >> x >> y >> z;
edg . push_back ( { x , y } );
gr [x] . push_back ( { y , z } );
gr [y] . push_back ( { x , z } );
}
for ( int i = 1 ; i <= n ; i ++ ) stt [i][0] = 1e16;
for ( int i = 0 ; i < s ; i ++ )
{
int x;
cin >> x;
stt [x][0] = 0;
}
go ( e , 0 );
for ( int i = 1 ; i <= 21 ; i ++ )
{
for ( int j = 1 ; j <= n ; j ++ )
{
long long nxt = st [j][ i - 1 ] , dis = sum [j] - sum [nxt];
st [j][i] = st [nxt][ i - 1 ];
stt [j][i] = min ( stt [j][ i - 1 ] , stt [nxt][ i - 1 ] + dis );
}
}
while ( q -- )
{
int x , y;
cin >> x >> y;
int a = edg [ x - 1 ] . first , b = edg [ x - 1 ] . second;
if ( dp [a] < dp [b] ) a = b;
if ( lca ( y , a ) != a )
{
cout << "escaped" << endl;
continue;
}
long long dif = dp [y] - dp [a] + 1 , ans = 1e17 , oy = y;
for ( int i = 0 ; i <= 21 ; i ++ )
{
if ( ( dif & ( 1 << i ) ) )
{
long long ad = sum [oy] - sum [y];
ans = min ( ans , ad + stt [y][i] );
y = st [y][i];
}
}
if ( ans >= 1e16 ) cout << "oo" << endl;
else cout << ans << endl;
}
}
