function diagonalDifference(arr: number[][]): number {
   
    let matrixSize = arr.length;
		
    let sumFirstDiag = 0;
		
    let sumSecondDiag = 0;
    
    for (let rows = 0, cols = matrixSize-1; rows < matrixSize; rows ++, cols--){
        sumFirstDiag += arr[rows][rows];

        sumSecondDiag += arr[rows][cols];

    }
    const result = Math.abs(sumFirstDiag - sumSecondDiag);    
   
    return result;

}