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#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>

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

#define unordered_map __fast_unordered_map
template<class Key, class Value, class Hash = std::hash<Key>>
using unordered_map = __gnu_pbds::gp_hash_table<Key, Value, Hash>;

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<<endl; }
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

const int MaxN = 404;

int N, M;
vector<int> adj_next[MaxN];
bool is_forbidden[MaxN];
int max_path_from[MaxN];

void FindPaths() {
  fill_n(max_path_from, N, 0);

  for (int i = N - 1; i >= 0; --i) {
    if (is_forbidden[i]) { continue; }
    max_path_from[i] = 1;
    for (int j : adj_next[i])
      maxi(max_path_from[i], 1 + max_path_from[j]);
  }
}

int Bt(int num_to_remove) {
  FindPaths();

  if (num_to_remove == 0) {
    return *max_element(max_path_from, max_path_from + N);
  }

  // Find the longest path
  int path_vert = max_element(max_path_from, max_path_from + N) - max_path_from;
  vector<int> longest_path{path_vert};
  while (max_path_from[longest_path.back()] > 1) {
    const int v = longest_path.back();
    int next_vert = -1;
    for (int s : adj_next[v]) {
      if (max_path_from[v] == max_path_from[s] + 1) {
        next_vert = s;
        break;
      }
    }
    assert(next_vert != -1);
    longest_path.push_back(next_vert);
  }

  int answer = 1e9;
  for (int v : longest_path) {
    is_forbidden[v] = true;
    mini(answer, Bt(num_to_remove - 1));
    is_forbidden[v] = false;
  }

  return answer;
}

int32_t main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout << fixed << setprecision(11);
  cerr << fixed << setprecision(6);

  int K;
  cin >> N >> M >> K;
  for (int i = 0; i < M; ++i) {
    int u, v;
    cin >> u >> v;
    --u; --v;
    adj_next[u].PB(v);
  }

  cout << Bt(K) << "\n";
}