Input numbers in 2d array and swap the largest with the smallest number in Java

import java.util.Scanner;

public class Q4
{
    public static void main(String args[])
    {
        int a[][]=new int[3][3], r,c,lg=0,lr=0,lc=0,sm=0,srw=0,scl=0;
        Scanner sc=new Scanner(System.in);

        System.out.println("Enter 9 numbers");
        for(r=0; r<3; r++)
        {
            for(c=0; c<3; c++)
            {
                a[r][c]=sc.nextInt();
                if(r==0 && c==0)
                {
                    lg=a[r][c];
                    lr=r;
                    lc=c;
                    sm=a[r][c];
                    srw=r;
                    scl=c;
                }
                else if(a[r][c]>lg)
                {
                    lg=a[r][c];
                    lr=r;
                    lc=c;
                }
                else if(a[r][c]<sm)
                {
                    sm=a[r][c];
                    srw=r;
                    scl=c;
                }
            }
        }

        a[lr][lc]=sm;
        a[srw][scl]=lg;

        System.out.println("\nArray after interchanging largest with the smallest number");
        for(r=0; r<3; r++)
        {
            for(c=0; c<3; c++)
            {
                System.out.print(a[r][c]+" ");
            }
            System.out.println();
        }
    }
}