A = [[1,1,2,2,3,3,3,3,3,3,4,4,4,4,4,3,3,3,3,7,7,7,7,7,3,3,3,3,3,8],
[3,3,3,3,6,6,6,6,7,7,7,3,3,3,0,0,0],[5,5,5,3,3,3,2,2,2,8,8,8,3,3,3,3]]

for sub_list in A:
    total = 0
    prev = 0
    for item in sub_list:
        if prev != 3 and item == 3:
            total += 1
        prev = item
    print total

3
2
2

Sublist_0: 3
           [6,4,5]
Sublist_1: 2
           [4,3]
Sublist_2: 2
           [3,4]