/* -*- coding: utf-8 -*-
 *
 * 3512.cc:  No.3512 moesode - yukicoder
 */

#include<cstdio>
#include<algorithm>

using namespace std;

/* constant */

const int MAX_N = 200000;

/* typedef */

using ll = long long;

/* global variables */

int ies[MAX_N], oes[MAX_N], cs[MAX_N];

/* subroutines */

/* main */

int main() {
  int n, m, k;
  scanf("%d%d%d", &n, &m, &k);
  for (int i = 0; i < m; i++) {
    int u, v;
    scanf("%d%d", &u, &v);
    u--, v--;
    oes[u]++, ies[v]++;
  }

  ll id = 0;
  int oc = 0, l = 0;
  for (int i = 0; i < n; i++) {
    if (oes[i] > 0)
      oc++, id += max(0, k - ies[i]);
    else
      cs[l++] = max(0, k - ies[i]);
  }
  sort(cs, cs + l);

  for (int i = 0; oc <= k && i < l; i++)
    oc++, id += cs[i];

  printf("%lld\n", id);
  
  return 0;
}