ht1.py

n = 7
a = [-10, 0, 1, 2, 3, 4, 5]
m = 6
b = [11, 0, 1, 2, 3, 11]
l = 5
c = [100, 0, 1, 2, 3]


for i in range(n):
    if a[i] in b and a[i] in c:
        res = a[i]
        break

try:
    i = a.index(res)
    j = b.index(res)
    k = c.index(res)

    length = 1
    index = 2

    while True:
        if a[i:i + index] == b[j:j + index] == c[k:k + index]:
            length += 1
            index += 1
        else:
            break

    print(length)
except:
    print('Sequences have no subsequences')