#include<bits/stdc++.h>
namespace {
#pragma GCC diagnostic ignored "-Wunused-function"
#include<atcoder/all>
#pragma GCC diagnostic warning "-Wunused-function"
using namespace std;
using namespace atcoder;
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; i--)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
template<class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } else return false; }
template<class T> bool chmin(T& a, const T& b) { if (b < a) { a = b; return true; } else return false; }
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;

} int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, m, k;
  cin >> n >> m >> k;
  VI indeg(n), outdeg(n);
  rep(_, m) {
    int a, b;
    cin >> a >> b;
    a--, b--;
    indeg[b]++;
    outdeg[a]++;
  }
  int vsz = 0;
  ll todo = 0;
  VI vfree;
  rep(i, n) {
    if (outdeg[i]) {
      vsz++;
      todo += max(k - indeg[i], 0);
    } else {
      vfree.emplace_back(max(0, k - indeg[i]));
    }
  }
  sort(all(vfree));
  int vadd = max(0, k + 1 - vsz);
  rep(i, vadd) todo += vfree[i];
  cout << todo << '\n';
}