a = [
    [1, 2, 0, 4],
    [18, 2, 13, 2],
    [10, 3, 11, 3],
    [3, 7, 4, 100],
    [0, 1, 9, 2],
    [8, 1, 2, 0]
]

r = 0
for j in range(len(a[0])):
    for i in range(len(a)):
        if a[i][j] == 0:
            break
    else:
        r = r + 1
print(r)