Find the sum of the weights of edges of the Minimum-Cost Arborescence with the root r for a given weighted directed graph G = (V, E).

Constraints

* 1 ≤ |V| ≤ 100
* 0 ≤ |E| ≤ 1,000
* 0 ≤ wi ≤ 10,000
* G has arborescence(s) with the root r

Input


|V| |E| r
s0 t0 w0
s1 t1 w1
:
s|E|-1 t|E|-1 w|E|-1


, where |V| is the number of vertices and |E| is the number of edges in the graph. The graph vertices are named with the numbers 0, 1,..., |V|-1 respectively. r is the root of the Minimum-Cost Arborescence.

si and ti represent source and target verticess of i-th directed edge. wi represents the weight of the i-th directed edge.

Output

Print the sum of the weights the Minimum-Cost Arborescence.

Examples

Input

4 6 0
0 1 3
0 2 2
2 0 1
2 3 1
3 0 1
3 1 5


Output

6


Input

6 10 0
0 2 7
0 1 1
0 3 5
1 4 9
2 1 6
1 3 2
3 4 3
4 2 2
2 5 8
3 5 3


Output

11
/*
NOTE
*min_element(.begin(),.end())
*max_element(.begin(),.end())
priority_queue<> pq
 push()  pop() size()  top()
map<>
 find() begin() end() insert(map<>::value_type())
pair<>
sort(.begin(), .end())
sort(arr, arr+N)
sort(a, a+N, greater<int>())
binary_search(vc.begin(), vc.end(), x)  //binary_search???true, false?????????
vector<int>::iterator lit = lower_bound(vc.begin(), vc.end(), x);
  lower_bound?????????????????????"??\???"????????????????????????????????????????????¬???????????????
vector<int>::iterator uit = upper_bound(vc.begin(), vc.end(), x);
  upper_bound????????????????????????"?¶???????"?????????????????????????????????????????¬???????????????
*/
#include <iostream>
#include <cstdio>
#include <climits>
#include <cmath>
#include <cassert>
#include <algorithm>
#include <utility>
#include <vector>
#include <string>
#include <stack>
#include <queue>
#include <map>

#define MAX 100
#define INF 1<<20
#define LLINF 10e12 // 1<<31 // 2^31
#define REP(i,n) for(int i=0;i<n;i++)
#define FOR(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)
#define ALL(o) (o).begin(), (o).end()

using namespace std;
typedef long long ll;
//
typedef int Weight;
struct Edge
{
  int src, dst;
  Weight weight;
  Edge(int src, int dst, Weight weight) :
    src(src), dst(dst), weight(weight) { }
};
bool operator < (const Edge &e, const Edge &f)
{
  return e.weight != f.weight ? e.weight > f.weight : // !!INVERSE!! ???????????????????????????
    e.src != f.src ? e.src < f.src : e.dst < f.dst;
}
typedef vector<Edge> Edges;
typedef vector<Edges> Graph;
typedef vector<Weight> Array;
typedef vector<Array> Matrix;

void backward_traverse(int v, int s, int r, Matrix &g,
  vector<int> &no, vector< vector<int> > &comp,
  vector<int> &prev, vector<Weight> &mcost,
  vector<int> &mark, Weight &cost, bool &found) {
  const int n = g.size();
  if (mark[v]) {
    vector<int> temp = no;
    found = true;
    do {
      cost += mcost[v];
      v = prev[v];
      if (v != s) {
        while (comp[v].size() > 0) {
          no[comp[v].back()] = s;
          comp[s].push_back(comp[v].back());
          comp[v].pop_back();
        }
      }
    } while (v != s);
    for (int j = 0; j < n; ++j)
      if (j != r && no[j] == s)
        for (int i = 0; i < n; ++i)
          if (no[i] != s && g[i][j] < INF)
            g[i][j] -= mcost[ temp[j] ];
  }
  mark[v] = true;
  for (int i = 0; i < n; ++i)
    if (no[i] != no[v] && prev[ no[i] ] == v)
      if (!mark[ no[i] ] || i == s)
        backward_traverse(i, s, r, g,
            no, comp, prev, mcost, mark, cost, found);
}

Weight minimum_spanning_arborescence(int r, Matrix &g) {
  const int n = g.size();

  vector<int> no(n);
  vector< vector<int> > comp(n);
  for (int i = 0; i < n; ++i) {
    no[i] = i;
    comp[i].push_back(i);
  }
  Weight cost = 0;
  while (1) {
    vector<int> prev(n, -1);
    vector<Weight> mcost(n, INF);
    for (int i = 0; i < n; ++i) {
      for (int j = 0; j < n; ++j) {
        if (j == r) continue;
        if (no[i] != no[j] && g[i][j] < INF) {
          if (g[i][j] < mcost[ no[j] ]) {
            mcost[ no[j] ] = g[i][j];
            prev[ no[j] ] = no[i];
          }
        }
      }
    }
    bool stop = true;
    vector<int> mark(n);
    for (int i = 0; i < n; ++i) {
      if (i == r || mark[i] || comp[i].size() == 0) continue;
      bool found = false;
      backward_traverse(i, i, r, g,
          no, comp, prev, mcost, mark, cost, found);
      if (found) stop = false;
    }
    if (stop) {
      for (int i = 0; i < n; ++i)
        if (prev[i] >= 0)
          cost += mcost[i];
      return cost;
    }
  }
}
//

int main()
{
  cin.tie(0);
  ios::sync_with_stdio(false);
  // FROM HERE
  int V, E, r; cin >> V >> E >> r;
  Matrix G(V,Array(V,INF));
  REP(i,E)
  {
    int s, t, w; cin >> s >> t >> w;
    G[s][t] = w;
  }
  cout << minimum_spanning_arborescence(r,G) << endl;
  return 0;
}