Write a program in java to add matices

import java.util.Scanner;
class Matrix_leftDiagonalAdd
{
public static void main(String[]args)
{
Scanner ob=new Scanner(System.in);
int n[][]=new int[3][3];
for (int i=0;i<3;i++)
{
for (int j=0;j<3;j++)
{
n[i][j]=ob.nextInt();
}
}
for (int i=0;i<3;i++)
{
for (int j=0;j<3;j++)
{
System.out.print(n[i][j]+" ");
}
System.out.println();
}
int Sum=0;
for (int i=0;i<3;i++)
{
for (int j=0;j<3;j++)
{
if (i==j)
{
Sum=Sum+n[i][j];
break;
}
}
}
System.out.println("\n\n\n\nThe sum of left diagonal of a matrix is = "+Sum);
}
}