Sum of left diagonal and right diagonal

import java.util.Scanner;
public class LeftRightDiagonal
{
    public static void main()
    {
        int i,j,ld=0,rd=0;
        Scanner sc=new Scanner(System.in);
        System.out.println("enter size of rows & colums");
        int r=sc.nextInt();
        int c=r; 
        int arr[][]=new int[r][c];
        int k=r-1;
        System.out.println("enter the numbers");
        for(i=0;i<r;i++)
        {
            for(j=0;j<c;j++)
            {
                arr[i][j]=sc.nextInt();
            }
        }
        System.out.println("The matrix is ");
        for(i=0;i<r;i++)
        {
            for(j=0;j<c;j++)
            {
                System.out.print(arr[i][j]+ "  ");
            }
            System.out.println();
        }
        for(i=0;i<r;i++)
        {
            ld=ld+arr[i][i];
        }
        for(i=0;i<c;i++)
        {
            rd=rd+arr[i][k];
            k=k-1;
        }
        System.out.println("Sum of left diagonal:"+ld);
        System.out.println("Sum of right diagonal:"+rd);
    }
}