package main

import "fmt"

func main() {
	var (
		stuNum int
		drkNum int
	)
	if _, err := fmt.Scanln(&stuNum, &drkNum); err != nil {

	}

	stuMap := make([]int, drkNum)
	for i := 0; i < stuNum; i += 1 {
		var fav int

		if _, err := fmt.Scanln(&fav); err != nil {
		}
		fav -= 1
		stuMap[fav] += 1
	}

	total := 0
	others := 0
	for i := 0; i < drkNum; i += 1 {
		if stuMap[i] % 2 == 0{
			total += stuMap[i]
		}else {
			total += stuMap[i] - 1
			others += 1
		}
	}
	total += others/2 + others%2
	fmt.Println(total)
}

package main

import "fmt"

type point struct {
	total int
	next  int
	eat   int
	step  int
}

func main() {
	var (
		actions int
		total   int
	)
	if _, err := fmt.Scanln(&actions, &total); err != nil {

	}
	queue := make([]point, 1000000000)
	queue[0] = point{
		total: 1,
		next:  2,
		eat:   0,
		step:  1,
	}
	for i, e := 0, 1; i < e; i += 1 {
		p := queue[i]
		if p.step == actions && p.total == total {
			fmt.Println(p.eat)
			return
		}

		if p.step >= actions {
			continue
		}

		//fmt.Println(i, e, p)

		// eat
		if p.total >= 1 {
			queue[e] = point{
				total: p.total - 1,
				next:  p.next,
				eat:   p.eat + 1,
				step:  p.step + 1,
			}
			e += 1
		}

		// add
		queue[e] = point{
			total: p.total + p.next,
			next:  p.next + 1,
			eat:   p.eat,
			step:  p.step + 1,
		}
		e += 1
	}
}

package main

import "fmt"

func main() {
	var (
		actions int
		total   int
	)
	if _, err := fmt.Scanln(&actions, &total); err != nil {

	}

	tmp := 2*total - actions*actions - actions
	for j := 0; j < actions; j += 1 {
		if j*j-3*j-2*actions*j == tmp {
			fmt.Println(j)
		}
	}
}