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

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

    int N,M,K; cin >> N >> M >> K;
    vector<int> A(N),B(N);
    while(M--){
        int a,b; cin >> a >> b,a--,b--;
        A.at(a)++,B.at(b)++;
    }
    long long answer = 0;
    vector<int> out;
    vector<pair<int,int>> zero;
    for(int i=0; i<N; i++) if(A.at(i)) out.push_back(i);
    for(int i=0; i<N; i++) if(A.at(i) == 0) zero.push_back({B.at(i),i});
    sort(zero.rbegin(),zero.rend());
    for(auto [ign,pos] : zero) if(out.size() <= K) out.push_back(pos);
    for(auto pos : out) answer += max(0,K-B.at(pos));
    cout << answer << endl;
}