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#include <cstdio>
#include <vector>
#include <limits>
#include <set>

using namespace std;

vector<int> FindLongest(const vector<vector<int>>& e, set<int>& v) {
  vector<pair<int, int>> p(e.size(), make_pair(-1, -1));

  pair<int, int> start = make_pair(-1, -1);
  for (int i=e.size()-1; i>=0; --i) {
    if (v.find(i) != v.end()) continue;
    p[i] = make_pair(0, -1);
    for (int j : e[i]) {
      if (p[j].first + 1 > p[i].first) {
        p[i] = make_pair(p[j].first + 1, j); 
      }
    }
    if (p[i].first > start.first) {
      start = make_pair(p[i].first, i); 
    }
  }
  vector<int> longest;
  while (start.second != -1) {
    longest.push_back(start.second);
    start = p[start.second];
  }
  return longest;
}

vector<int> FindLongestRecursively(const vector<vector<int>>& e, set<int> v, int k) {
  vector<int> longest = FindLongest(e, v);
  if (k == 0) return longest;

  bool initialized = false;
  vector<int> result;
  for (int i : longest) {
    v.insert(i);
    vector<int> curr = FindLongestRecursively(e, v, k-1);
    v.erase(i);
    if (!initialized || curr.size() < result.size()) {
      initialized = true;
      result = curr;
    }
  }
  return result;
}

int main() {
  int n, m, k; scanf("%d %d %d", &n, &m, &k);
  
  vector<vector<int>> e(n);
  for (int i=0; i<m; ++i) {
    int x, y; scanf("%d %d", &x, &y); --x; --y;
    e[x].push_back(y);
  }

  vector<int> longest = FindLongestRecursively(e, set<int>(), k);
  printf("%d\n", (int)longest.size()); 

  return 0;
};