<?php
$N = int();
$di = new Di($N);
for($i = 0; $i < $N-1; $i++){
  list($from, $to, $d) = array_map("intval", explode(" ", trim(fgets(STDIN))));
  $di->connect($from, $to, $d);
  $di->connect($to, $from, $d);
}
list($Q, $K) = ints();
$di->solve($K);
$distance = $di->distance;
for($i = 0; $i < $Q; $i++){
    list($from, $to) = ints();
    echo $distance[$from]+$distance[$to],"\n";
}

/**
 * Dijkstra
 * Attention: 1-origin
 **/
class Di{
  public $pq;
  public $distance;
  public $graph;
  public $from;
  public $inf = 10**18;
  function __construct($n) {
    $this->pq = new SplPriorityQueue();
    for($i = 1; $i <= $n; $i++){
      $this->distance[$i] = $this->inf;
      $this->from[$i] = 0;
    }
  }
  function connect($from, $to, $cost){
    $this->graph[$from][] = [$to, $cost];
  }
  function solve($from){
    $this->pq->insert($from, 0);
    $this->distance[$from] = 0;
    while($this->pq->count()){
      $f = $this->pq->extract();
      if(!isset($this->graph[$f]))continue;
      foreach($this->graph[$f] as list($t, $dist)){
        $new = $this->distance[$f] + $dist;
        if($this->distance[$t] > $new){
          $this->distance[$t] = $new;
          $this->from[$t] = $f;
          $this->pq->insert($t, -$new);
        }
      }
    }
  }
}


function str(){
  return trim(fgets(STDIN));
}
function ints(){
  return array_map("intval", explode(" ", trim(fgets(STDIN))));
}
function int(){
  return intval(trim(fgets(STDIN)));
}
function chmax(&$a,$b){if($a<$b){$a=$b;return 1;}return 0;}
function chmin(&$a,$b){if($a>$b){$a=$b;return 1;}return 0;}

function o(...$val){
    if(count($val)==1)$val = array_shift($val);
    $trace = debug_backtrace();
    echo $trace[0]['line'].")";
    if(is_array($val)){
        if(count($val) == 0){
            echo "empty array";
        }elseif(!is_array(current($val))){
            echo "array: ";
            echo implode(" ", addIndex($val))."\n";
        }else{
            echo "array:array\n";
            if(isCleanArray($val)){
                foreach($val as $row)echo implode(" ", addIndex($row))."\n";
            }else{
                foreach($val as $i => $row)echo "[".$i."] ".implode(" ", addIndex($row))."\n";
            }
        }
    }else{
        echo $val."\n";
    }
}
function addIndex($val){
    if(!isCleanArray($val)){
        $val = array_map(function($k, $v){return $k.":".$v;}, array_keys($val), $val);
    }
    return $val;
}
function isCleanArray($array){
    $clean = true;
    $i = 0;
    foreach($array as $k => $v){
        if($k != $i++)$clean = false;
    }
    return $clean;
}
/**
 * 座圧対象の配列を渡すと以下の値を返す
 * ・圧縮された配列
 * ・復元用のMap
 * ・圧縮用のMap
 **/
function atsu($array){
    $a = array_flip($array);
    $fuku = array_flip($a);
    sort($fuku);
    $atsu = array_flip($fuku);
    foreach($array as $i => $val)$array[$i] = $atsu[$val];
    return [$array, $fuku, $atsu];
}
//配列の最大公約数
function gcdAll($array){
    $gcd = $array[0];
    for($i = 1; $i < count($array); $i++){
        $gcd = gcd($gcd, $array[$i]);
    }
    return $gcd;
}

//最大公約数
function gcd($m, $n){
    if(!$n)return $m;
    return gcd($n, $m % $n);
}

//配列の最小公倍数
function lcmAll($array){
    $lcm = $array[0];
    for($i = 1; $i < count($array); $i++){
        $lcm = lcm($lcm, $array[$i]);
    }
    return $lcm;
}

//最小公倍数
function lcm($a, $b) {
    return $a / gcd($a, $b) * $b;
}
//ビットカウント-1の数を数える
function popcount($x){
    $con = 0;
    while ($x) {
        $x &= $x-1;
        ++$con;
    }
    return $con;
}


Measured memory_bytes: 175728