Sum Of Double Dimensional Array Diagonals

import java.io.*;

public class sumofdiagonals
{ public static void main(String args[]) throws IOException
{ InputStreamReader read = new InputStreamReader(System.in);
BufferedReader br = new BufferedReader(read);

int arr[][] = {{6,9,0,8},{3,2,1,5},{2,9,0,1},{4,1,9,6}};
int sum=0;
for(int i=0;i<4;i++)
{ for(int j=0;j<4;j++)
{ if(i==j)
sum+=arr[i][j];
}
}
System.out.println(sum);
}
}