function diagonalDifference(arr) {
    const maxIndex = arr.length - 1;
    let diag1 = 0;
    let diag2 = 0;
    for (let i = 0; i < arr.length; i++) {
        diag1 += arr[i][i]
        diag2 += arr[i][maxIndex - i]
    }
    return Math.abs(diag1 - diag2);
}