def bubble_sort(arr):
    for i in range(len(arr)-1):
        for j in range(len(arr)-i-1):
            if arr[j] > arr[j+1]:
                arr[j],arr[j+1] = arr[j+1],arr[j]
    
    
arr = [6,4,2,8,9,12,0]
bubble_sort(arr)
print(arr)