Getting 2 zeroes instead of one

import java.util.*;
public class Main {
public static void main(String args[]) {

	Scanner scn = new Scanner(System.in);
	int n = scn.nextInt();
	int nsp=4*n-2;
	
	int row=1;int num=n;
	int i;
	while(row<=2*n+1)
	{  
		for(i=n;i>=num;i--)
		{ 
			
		System.out.print(i+" ");
		}
		for(i=1;i<=nsp;i++)
		{
			System.out.print(" ");
		}
		for(i=num;i<=n;i++)
		{
			System.out.print(i+" ");
		}
		if(row<=n)
		{
			num-=1;nsp-=4;
		}
		
		else
		{
			num+=1;nsp+=4;
		}
		System.out.print("\n");
		row+=1;
	}

}

}

the above mentioned is my code