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#include "bits/stdc++.h"
#pragma GCC optimize ("unroll-loops")

using namespace std;
#define PB push_back
#define LL long long
#define FOR(i,a,b) for (int i = (a); i <= (b); i++)
#define FORD(i,a,b) for (int i = (a); i >= (b); i--)
#define REP(i,n) FOR(i,0,(int)(n)-1)
#define st first
#define nd second
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) ((int)(x).size())
#define VI vector<int>
#define PII pair<int,int>
#define LD long double

template<class C> void mini(C& a4, C b4) { a4 = min(a4, b4); }
template<class C> void maxi(C& a4, C b4) { a4 = max(a4, b4); }

template<class TH> void _dbg(const char *sdbg, TH h){cerr<<sdbg<<"="<<h<<"\n";}
template<class TH, class... TA> void _dbg(const char *sdbg, TH h, TA... a) {
  while(*sdbg!=',')cerr<<*sdbg++;cerr<<"="<<h<<","; _dbg(sdbg+1, a...);
}

template<class T> ostream &operator<<(ostream &os, vector<T> V){
  os<<"[";for(auto vv:V)os<<vv<<",";return os<<"]";
} 

template<class L, class R> ostream &operator<<(ostream &os, pair<L,R> P) {
  return os << "(" << P.st << "," << P.nd << ")";
}


#ifdef LOCAL
#define debug(...) _dbg(#__VA_ARGS__, __VA_ARGS__)
#else
#define debug(...) (__VA_ARGS__)
#define cerr if(0)cout
#endif

struct fu{
  VI f;
  fu(int n){
    f.resize(n);
    iota(ALL(f), 0);
  }
  int fi(int x){
    return f[x] == x? x : f[x] = fi(f[x]);
  }
  void un(int x, int y){
      f[fi(x)] = fi(y);
  }
};
vector<VI> graph;
vector<VI> rgraph;
vector<bool> del;
int n;

VI longest_path(){
  VI res(n, 0);
  PII r = {0, -1};
  REP(i, n){
    maxi(r, {res[i], i});
    if(del[i])
      continue;
    for(int a: graph[i]){
      if(del[a])
        continue;
      maxi(res[a], res[i] + 1);
    }
  }
  int cur = r.nd;
  VI path = {cur};
  while(cur != -1 && res[cur]){
    for(int a: rgraph[cur]){
      if(del[a])
        continue;
      if(res[a] == res[cur] - 1){
        cur = a;
        path.PB(a);
        break;
      }
    }
  }
  return path;
}

int bt(int k){
  VI p = longest_path();
  if(k == 0){
    return SZ(p);
  }
  int sc = INT_MAX;
  for(int a: p){
    del[a] = true;
    mini(sc, bt(k - 1));
    del[a] = false;
  }
  return sc;
}

int32_t main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int m,k;
  cin>>n>>m>>k;
  if(k >= n){
    cout<<0<<"\n";
    return 0;
  }
  graph.resize(n);
  rgraph.resize(n);
  del.resize(n);
  REP(i, m){
    int a,b;
    cin>>a>>b;
    a--;
    b--;
    graph[a].push_back(b);
    rgraph[b].push_back(a);
  }
  cout<<bt(k)<<"\n";
}