package main

import . "fmt"
import . "os"
import bf "bufio"
import . "sort"

func main() {
	rd:=bf.NewReader(Stdin)
	var n,m,k int
	Fscan(rd,&n,&m,&k)
	eIn := make([]int, n+1)
	eOut := make([]int, n+1)
	for i := 0; i < m; i++ {
		var a, b int
		Fscan(rd,&a,&b)
		eOut[a]++
		eIn[b]++
	}
	outs := 0
	ins := 0
	idles := make([]int, 0, n)
	for e, c := range eOut {
		if c > 0 {
			outs++
			ins += eIn[e]
		} else {
			idles = append(idles, eIn[e])
		}
	}
	if k < outs {
		needs := max(0, outs * k - ins)
		Println(needs)
		return
	}
	Sort(Reverse(IntSlice(idles)))
	for _, c := range idles[:k+1-outs] {
		ins += c
	}
	ans := max(0, (k+1)*k - ins)
	Println(ans)
}