Codeforces 233A PerfectPermutation in java

PerfectPermutation.java

import java.util.Scanner;
public class PerfectPermutation
{
	public static void main(String[] args)
	{
		Scanner z=new Scanner(System.in);
		int n=z.nextInt();
		int arr[]=new int[n];
		for(int i=0;i<n;i++)
			arr[i]=i+1;
		int temp;
		if(n%2==0) {
			for(int i=1;i<n;i+=2) {
				temp=arr[i];
				arr[i]=arr[i-1];
				arr[i-1]=temp;
			}
			for(int a:arr)
				System.out.print(a+" ");
		}
		else
			System.out.println(-1);
	}
}