def diagonalDifference(arr):
    n = 0
    lr = 0
    rl = 0
    for x in arr:
        lr += x[n]
        n+=1 
    
    for x in arr:
        rl += x[n-1]
        n-=1 
    
    return lr - rl if lr - rl > 0 else (lr - rl) * -1