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#include <iostream>
#include <vector>
#include <queue>
#include <algorithm>
#include <set>
#include <map>
#include <bits/stdc++.h>


using namespace std;


int result = 1000;
vector<int> v[305];
int n; int m;
int d[305];
bool blocked[305];

vector<int> f()
{
  vector<int> path;

  int max_dist = 0;
  int ix = 0;

  for(int i=n; i>=1; i--)
  {
    if(blocked[i]) continue;
    d[i] = 1;
    for(int x : v[i])
    {
      if(blocked[x])
        continue;
      d[i] = max(d[i], d[x] + 1);
    }

    if(d[i] > max_dist)
    { max_dist = d[i]; ix = i;}
  }

  result = min(result, max_dist);

  for(int i=0; i<max_dist; i++)
  {
    path.push_back(ix);
    for(int x : v[ix])
      if(d[x] + 1 == d[ix])
      {
        ix = x;
        break;
      }
  }

  return path;
}

void g(int k)
{
  auto path = f();
  if(k == 0) return;
  for(int x : path)
  {
    blocked[x] = 1;
    g(k-1);
    blocked[x] = 0;
  }
}

int main()
{
  ios::sync_with_stdio(0);
  int k; 
  cin >> n >> m >> k; for(int i=0; i<m; i++) {int a,b; cin >> a >> b; v[a].push_back(b);}

  g(k);
  cout << result << endl;
}