diagonal difference hackerrank solution in java 8 using list

Java
 public static int diagonalDifference(List<List<Integer>> arr) {
    // Write your code here
    int leftd=0;
    int rightd=0;
    int n=arr.size();
    for(int i=0;i<n;i++)
    {
        leftd+=arr.get(i).get(i);
        rightd+=arr.get(i).get(n-i-1);
    }
    int absd=Math.abs(leftd-rightd);
    return absd;

    }prim =0
    sec=0
    length = len(arr[0])
    for count in range(length):
        prim += arr[count][count]
        sec += arr[count][(length-count-1)]
    return abs(prim-sec)
    
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