#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
#define ll long long
#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define repl(i,a,b) for(ll i=(a);i<(b);i++)
#define all(a) (a).begin(),(a).end()
#define rall(a) (a).rbegin(),(a).rend()

template <typename T> bool chmin(T &a,T b){if(a>b){a=b;return true;} return false;}
template <typename T> bool chmax(T &a,T b){if(a<b){a=b;return true;} return false;}


void solve(){
  int n,m,k; cin >> n >> m >> k;
  vector<int> degin(n),degout(n);
  rep(i,0,m){
    int a,b; cin >> a >> b;
    a--,b--;
    degin[b]++;
    degout[a]++;
  }
  int cnt1=0,cnt2=0;
  rep(i,0,n){
    if(degin[i])cnt1++;
    if(degout[i])cnt2++;
  }
  ll ans=0;
  rep(i,0,n){
    if(degout[i]){
      ans+=max(0,k-degin[i]);
      // cout << i << " " << ans << "\n";
    }
  }
  ll tmp=0;
  rep(i,0,n){
    if(degout[i]){
      chmax(tmp,(ll)k-degin[i]-cnt2+1);
    }
    else{
      chmax(tmp,(ll)k-degin[i]-cnt2);
    }
  }
  vector<int> v;
  rep(i,0,n){
    if(degout[i] == 0) v.push_back(degin[i]);
  }
  sort(rall(v));
  rep(i,0,tmp) ans+=max(0,k-v[i]);
  cout << ans << "\n";

  return;
}

int main(){
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  int T=1;
  // cin >> T;
  while(T--) solve();
}