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#include <bits/stdc++.h>
using namespace std;

const int inf = 1000 * 1000 * 1000 + 7;

using Graph = vector<vector<int>>;

vector<int> getLongestPath(const Graph& g, const set<int>& d) {
  int n = (int) g.size();
  vector<int> f(n, 1), nxt(n, -1);
  int s = -1;
  for (int v = n - 1; v >= 0; --v) {
    if (d.count(v)) {
      f[v] = -inf;
      continue;
    }
    for (int to: g[v]) {
      if (f[v] < f[to] + 1) {
        f[v] = f[to] + 1;
        nxt[v] = to;
      }
    }
    if (s == -1 || f[v] > f[s]) {
      s = v;
    }
  }
  
  vector<int> path;
  while (s != -1) {
    path.push_back(s);
    s = nxt[s];
  }
  return path;
}

int solve(const Graph& g, set<int> d, int k) {
  auto path = getLongestPath(g, d);
  
  if (k == 0) {
    return (int) path.size();
  }
  
  int result = inf;
  for (int v: path) {
    d.insert(v);
    result = min(result, solve(g, d, k - 1));
    d.erase(v);
  }
  
  return result;
}

int solve(Graph g, int k) {
  return solve(g, set<int>(), k);
}

int solveInput() {
  int n, m, k;
  cin >> n >> m >> k;
  
  Graph g(n);
  for (int i = 0; i < m; ++i) {
    int x, y;
    cin >> x >> y;
    g[x - 1].push_back(y - 1);
  }
  
  return solve(g, k);
}

int brute(Graph g, set<int> d, int k) {
  int n = (int) g.size();
  auto path = getLongestPath(g, d);
  
  if (k == 0) {
    return (int) path.size();
  }
  
  int result = inf;
  for (int v = 0; v < n; ++v) {
    if (d.count(v)) {
      continue;
    }
    d.insert(v);
    result = min(result, brute(g, d, k - 1));
    d.erase(v);
  }
  return result;
}

int brute(Graph g, int k) {
  return brute(g, set<int>(), k);
}

Graph genRandomGraph(int n, int m) {
  Graph g(n);
  set<pair<int, int>> s;
  for (int i = 0; i < m; ++i) {
    int x = rand() % n;
    int y = rand() % n;
    if (x > y) {
      swap(x, y);
    }
    if (x == y || s.count({x, y})) {
      --i;
      continue;
    }
    g[x].push_back(y);
    s.insert({x, y});      
  }
  
  return g;
}

void stress() {
  for (int len = 1; len <= 6; ++len) {
    cerr << "All: " << len << endl;
    vector<pair<int, int>> edges;
    for (int i = 0; i < len; ++i)
      for (int j = 0; j < i; ++j)
        edges.emplace_back(j, i);
    int m = (int) edges.size();
    for (int i = 0; i < (1 << m); ++i) {
      Graph g(len);
      for (int j = 0; j < m; ++j) {
        if (i & (1 << j)) {
          g[edges[j].first].push_back(edges[j].second);
        }
      }
      for (int k = 0; k <= min(4, len); ++k) {
        assert(brute(g, k) == solve(g, k));
      }
    }
  }
  cerr << "Correct on small!" << endl;
  for (int i = 0; i < 100; ++i) {
    Graph g = genRandomGraph(300, 400);
    int k = rand() % 3;
    assert(brute(g, k) == solve(g, k));
    cerr << i << endl;
  }
  cerr << "Correct on random with small k" << endl;
  for (int i = 0; i < 100; ++i) {
    auto start = clock();
    Graph g = genRandomGraph(300, 400);
    int k = rand() % 5;
    int r = solve(g, k);
    auto end = clock();
    cerr << i << ", time:" << (end - start + .0) / CLOCKS_PER_SEC << " : " << r << endl;
  }
  cout << "Fast? :)" << endl;
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  
  cout << solveInput() << '\n';
}