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#include <bits/stdc++.h>
// #pragma GCC optimize ("O3")
// #pragma GCC target ("sse4")
using namespace std;

typedef long long LL;
typedef unsigned long long ULL;
typedef pair<int,int> PII;

#define REP(i,n) for(int i=0;i<(n);++i)
#define FOR(i,a,b) for (int i=(a); i<(b); ++i)
#define FORD(i,a,b) for (int i=(a)-1; i>=(b); --i)

#define pb push_back
#define mp make_pair
#define st first
#define nd second

int N, M, K;
vector<int> adj[500];

int DP[500];
bool removed[500];
int p[500];

int go(int K) {
  REP(i,N) {
    DP[i] = !removed[i];
    p[i] = -1;
  }

  int max_chain = -1;
  int max_chain_end = -1;
  REP(u,N) if (!removed[u]) {
    for (auto v: adj[u]) if (DP[v] < DP[u] + 1) {
      DP[v] = DP[u] + 1;
      p[v] = u;
    }
    if (DP[u] > max_chain) {
      max_chain = DP[u];
      max_chain_end = u;
    }
  }

  int result = max_chain;
  if (!K) return result;

  vector<int> candidates;
  while (max_chain_end != -1) {
    candidates.pb(max_chain_end);
    max_chain_end = p[max_chain_end];
  }

  for (auto v: candidates) {
    removed[v] = true;
    result = min(result, go(K-1));
    removed[v] = false;
  }
  return result;
}

int main(int argc, char* argv[]) {
  scanf("%d%d%d", &N, &M, &K);
  REP(i,M) {
    int u, v;
    scanf("%d%d", &u, &v);
    --u, --v;
    adj[u].pb(v);
  }
  if (K >= N) {
    printf("0\n");
    return 0;
  }
  int result = go(K);
  printf("%d\n", result);
}