package main

import . "fmt"

func main() {
	var n,m int
	Scan(&n,&m)
	f:=make([]int,n+1)
	for ;m>0;m-- {
		var a,b int
		Scan(&a,&b)
		n+=f[b]-1
		f[b]=1
	}
	Println(n)
}