// see https://github.com/LumaKernel/vimfiles/tree/master/snippets/cp-cpp/temp.snip
/// --- .lumrc Template {{{ ///
#if 0
#define assert(...)
#endif
#include <bits/stdc++.h>
using namespace std;

using ll = long long;
using ull = unsigned long long;
using ld = long double;
using P = tuple<ll, ll>;
using P3 = tuple<ll, ll, ll>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VP = vector<P>;
using VVP = vector<VP>;
using VS = vector<string>;

#define omajinai ios::sync_with_stdio(false);cin.tie(0)

#define FOR(i,a,b) for(int i=int(a);i<int(b);++i)
#define FORI(i,a,b) for(int i=int(a);i<=int(b);++i)
#define REP(i,n) FOR(i,0,n)
#define REPI(i,n) FORI(i,0,n)
#define RFOR(i,a,b) for(int i=int(b)-1;i>=int(a);--i)
#define RFORI(i,a,b) for(int i=int(b);i>=int(a);--i)
#define RREP(i,n) RFOR(i,0,n)
#define RREPI(i,n) RFORI(i,0,n)

#define ALL(a) (a).begin(),(a).end()
#define UNIQUE(a) (a).erase(unique(ALL(a)),(a).end())
#define PB push_back
#define EACH(i,c) REP(i,(c).size())
#define REACH(i,c) RREP(i,(c).size())
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort(ALL(c))

#define BR cout<<"\n";

#ifdef DEBUG
#define dump(...) cerr<<"["<<__LINE__<< "] "<<#__VA_ARGS__<<" = "<<make_tuple(__VA_ARGS__)<<"\n";
#else
#define dump(...)
#endif

#define YES(x) cout<<((x)?"YES":"NO")<<"\n";
#define Yes(x) cout<<((x)?"Yes":"No")<<"\n";
#define yes(x) cout<<((x)?"yes":"no")<<"\n";

inline int omajinai_int_in(){omajinai;int n;cin>>n;return n;}
inline ll omajinai_ll_in(){omajinai;ll n;cin>>n;return n;}
inline string omajinai_string_in(){omajinai;string n;cin>>n;return n;}
inline int int_in(){int n;cin>>n;return n;}
inline ll ll_in(){ll n;cin>>n;return n;}
inline string string_in(){string n;cin>>n;return n;}
#define oini omajinai_int_in()
#define oinl omajinai_ll_in()
#define oins omajinai_string_in()
#define ini int_in()
#define inl ll_in()
#define ins string_in()

#define isInside(y,x) (0<=(y)&&(y)<h&&0<=(x)&&(x)<w)

#define fi(x) (get<0>(x))
#define se(x) (get<1>(x))
#define th(x) (get<2>(x))
#define fo(x) (get<3>(x))
#define fif(x) (get<4>(x))

template <typename T> ostream &operator<<(ostream &o, const vector<T> &v) { o << '{'; EACH(i, v) o << v[i] << (i != v.size()-1 ? ", " : ""); o << "}";  return o; }

template<int n, class...T> typename enable_if<(n>=sizeof...(T))>::type _ot(ostream &, tuple<T...> const &){}
template<int n, class...T> typename enable_if<(n< sizeof...(T))>::type _ot(ostream & os, tuple<T...> const & t){ os << (n==0?"":", ") << get<n>(t); _ot<n+1>(os, t); }
template<class...T> ostream & operator<<(ostream & os, tuple<T...> const & t){ _ot<0>(os, t); return os; }

template <typename T> inline void smax(T &a, T b) { a = a > b ? a : b; }
template <typename T> inline void smin(T &a, T b) { a = a < b ? a : b; }

constexpr double PI = acos(-1);

/// }}}--- ///

constexpr int INF = 1e9+1;
constexpr ll LINF = 1e18+1;
constexpr int MOD = 1e9+7;


struct StronglyConnectedComponent {
  VVI g, rev;
  VI topo;
  VI used;
  VI comp;
  int n;
  StronglyConnectedComponent(int n): n(n), g(n), rev(n), used(n, 0), comp(n, -1){}
  void dfs1(int i) {
    if(used[i]) return;
    used[i] = 1;
    for(int j : g[i]) dfs1(j);
    topo.PB(i);
  }
  void dfs2(int i, int num) {
    if(comp[i] != -1) return;
    comp[i] = num;
    for(int j : rev[i]) dfs2(j, num);
  }
  void addEdge(int a, int b) {
    g[a].PB(b);
    rev[b].PB(a);
  }
  int operator[](int i) {
    return comp[i];
  }
  void decomposite(VVI &t) {
    REP(i,n) if(!used[i]) dfs1(i);
    reverse(begin(topo), end(topo));
    int k=0;
    EACH(i, topo) if(comp[i] != -1) dfs2(i, k++);

    t.resize(n);
    set<P> connect;
    REP(i,n){
      for(int j : g[i]) {
        int x = comp[i], y = comp[j];
        if(x == y) continue;
        if(connect.count(P(x, y))) continue;
        connect.emplace(x, y);
      }
    }
  }
};

int MSTArborescence(VVP &graph, int start, int sum = 0) {
  int n = graph.size();

  VI rev(n, -1), weight(n, INF);
  REP(idx, n) {
    for(auto &e : graph[idx]) {
      if(se(e) < weight[fi(e)]) {
        weight[fi(e)] = se(e);
        rev[fi(e)] = idx;
      }
    }
  }

  StronglyConnectedComponent scc(n);
  REP(i, n) {
    if(start == i) continue;
    scc.addEdge(rev[i], i);
    sum += weight[i];
  }
  VVI renew;
  scc.decomposite(renew);
  if(renew.size() == n) return sum;
  VVP fixed(renew.size());
  REP(i, n) {
    for(auto &e : graph[i]) {
      if(scc[i] == scc[fi(e)]) continue;
      fixed[scc[i]].emplace_back(scc[fi(e)], se(e) - weight[fi(e)]);
    }
  }
  return MSTArborescence(fixed, scc[start], sum);
}

int main() {
  int n=oini,m=ini,r=ini;
  VVP graph(n);
  REP(i,m) {
    int a=ini,b=ini,c=ini;
    graph[a].emplace_back(b, c);
  }
  cout << MSTArborescence(graph, r) << endl;
}

//

