#define _GLIBCXX_DEBUG
#include <iostream>
#include <vector>
#include <stdio.h>
#include <bits/stdc++.h>


using namespace std;
#define ll long long
#define ld long double
#define  P pair<ll,ll>
#define FOR(i,n,m) for(ll i=n; i<(ll)m;i++)
#define FORa(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)
#define FORr(i,m,n) for(ll i=n; i>=(ll)m; i--)
#define FORm(i,m) for(auto i=m.begin();i!=m.end();i++)
#define REP(i,n) for(int i=0;i<(int)n;++i)
#define ALL(c) (c).begin(), (c).end()
#define VEC2(x,a,b) vector<vector<ll>> x = vector<vector<ll>>(a,vector<ll>(b,0))
#define sortAl(v) sort(v.begin(),v.end())
#define sortAlr(v) sort(v.begin(),v.end()); reverse(v.begin(),v.end())
#define cinv(v,n,m) FOR(i,n,m) cin>>v.at(i)
#define coutv(v,n,m) FOR(i,n,m) cout<<v.at(i) <<" "; cout<<endl
#define cout(n) cout<<fixed<<setprecision(n)


//    Edges := 重み付き辺の集合
//    WeightedGraph := 重み付きグラフ
//    UnWeightedGraph := 重み無しグラフ
//    Matrix := 距離行列
template< typename T >
struct edge {
  ll src, to;
  T cost;

  edge(ll to, T cost) : src(-1), to(to), cost(cost) {}

  edge(ll src, ll to, T cost) : src(src), to(to), cost(cost) {}

  edge &operator=(const int &x) {
    to = x;
    return *this;
  }

  operator ll() const { return to; }
};

template< typename T >
using Edges = vector< edge< T > >;
template< typename T >
using WeightedGraph = vector< Edges< T > >;
using UnWeightedGraph = vector< vector< ll > >;
template< typename T >
using Matrix = vector< vector< T > >;

struct UnionFind
{
  vector< int > data;

  UnionFind(int sz)
  {
    data.assign(sz, -1);
  }

  bool unite(int x, int y)
  {
    x = find(x), y = find(y);
    if(x == y) return(false);
    if(data[x] > data[y]) swap(x, y);
    data[x] += data[y];
    data[y] = x;
    return(true);
  }

  int find(int k)
  {
    if(data[k] < 0) return(k);
    return(data[k] = find(data[k]));
  }

  int size(int k)
  {
    return(-data[find(k)]);
  }
};



// 計算量 ElogV


template< typename T, typename E = T >
struct SkewHeap
{
  using G = function< T(T, E) >;
  using H = function< E(E, E) >;

  struct Node
  {
    T key;
    E lazy;
    Node *l, *r;
  };

  const bool rev;
  const G g;
  const H h;

  SkewHeap(bool rev = false) : g([](const T &a, const E &b) { return a + b; }),
                               h([](const E &a, const E &b) { return a + b; }), rev(rev) {}

  SkewHeap(const G &g, const H &h, bool rev = false) : rev(rev), g(g), h(h) {}

  Node *propagate(Node *t)
  {
    if(t->lazy != 0) {
      if(t->l) t->l->lazy = h(t->l->lazy, t->lazy);
      if(t->r) t->r->lazy = h(t->r->lazy, t->lazy);
      t->key = g(t->key, t->lazy);
      t->lazy = 0;
    }
    return t;
  }

  Node *merge(Node *x, Node *y)
  {
    if(!x || !y) return x ? x : y;
    propagate(x), propagate(y);
    if((x->key > y->key) ^ rev) swap(x, y);
    x->r = merge(y, x->r);
    swap(x->l, x->r);
    return x;
  }

  void push(Node *&root, const T &key)
  {
    root = merge(root, new Node({key, 0, nullptr, nullptr}));
  }

  T top(Node *root)
  {
    return propagate(root)->key;
  }

  void pop(Node *&root)
  {
    propagate(root);
    auto *temp = root;
    root = merge(root->l, root->r);
    delete temp;
  }

  bool empty(Node *root) const
  {
    return !root;
  }

  void add(Node *root, const E &lazy)
  {
    if(root) {
      root->lazy = h(root->lazy, lazy);
      propagate(root);
    }
  }

  Node *makeheap()
  {
    return nullptr;
  }
};

template< typename T >
struct MinimumSpanningTreeArborescence
{
  using Pi = pair< T, int >;
  using Heap = SkewHeap< Pi, int >;
  using Node = typename Heap::Node;
  const Edges< T > &es;
  const int V;
  T INF;

  MinimumSpanningTreeArborescence(const Edges< T > &es, ll V) :
       es(es), V(V), INF(numeric_limits< T >::max()) {}

  T build(int start)
  {
    auto g = [](const Pi &a, const T &b) { return Pi(a.first + b, a.second); };
    auto h = [](const T &a, const T &b) { return a + b; };
    Heap heap(g, h);
    vector< Node * > heaps(V, heap.makeheap());
    for(auto &e : es) heap.push(heaps[e.to], {e.cost, e.src});
    UnionFind uf(V);
    vector< int > used(V, -1);
    used[start] = start;

    T ret = 0;
    for(int s = 0; s < V; s++) {
      stack< int > path;
      for(int u = s; used[u] < 0;) {
        path.push(u);
        used[u] = s;
        if(heap.empty(heaps[u])) return -1;
        auto p = heap.top(heaps[u]);
        ret += p.first;
        heap.add(heaps[u], -p.first);
        heap.pop(heaps[u]);
        int v = uf.find(p.second);
        if(used[v] == s) {
          int w;
          Node *nextheap = heap.makeheap();
          do {
            w = path.top();
            path.pop();
            nextheap = heap.merge(nextheap, heaps[w]);
          } while(uf.unite(v, w));
          heaps[uf.find(v)] = nextheap;
          used[uf.find(v)] = -1;
        }
        u = uf.find(v);
      }
    }
    return ret;
  }
};


int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    ll v,e,r;
    cin>>v>>e>>r;
    Edges<ll> edges;
    FOR(i,0,e){
      ll in1,in2,c;
      cin>>in1>>in2>>c;
      edges.push_back(edge<ll>(in1,in2,c));
    }
    MinimumSpanningTreeArborescence<ll> res = {edges,v};
    cout<<res.build(r)<<endl;
}



Measured memory_bytes: 3296