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#include <iostream>
#include <vector>
using namespace std;
const int N = 301;
int n, res = 300;
vector<int> v[N];
pair<int, int> longest[N];
bool removed[N];
void rec_solve(int k) {
  pair<int, int> best;
  for (int i=1; i<=n; i++) longest[i] = make_pair(1, 0);
  for (int i=1; i<=n; i++) {
    if (removed[i]) continue;
    best = max(best, make_pair(longest[i].first, i));
    for (int x: v[i]) longest[x] = max(longest[x], make_pair(longest[i].first+1, i));
  }
  res = min(res, best.first);
  if (k > 0) {
    vector<int> path;
    int x = best.second;
    while (x) {
      path.push_back(x);
      x = longest[x].second;
    }
    for (int x: path) {
      removed[x] = true;
      rec_solve(k-1);
      removed[x] = false;
    }
  }
}
int main() {
  ios_base::sync_with_stdio(0);
  int m, k, x, y;
  cin >> n >> m >> k;
  if (k >= n) {
    printf("0\n");
    return 0;
  }
  while (m--) {
    cin >> x >> y;
    v[x].push_back(y);
  }
  rec_solve(k);
  cout << res << "\n";
  return 0;
}