Envío 2059

Código

# Knuth-Morris-Pratt Algorithm
def get_longest_border(string):
    length = len(string)
    border_length_prefix = [0] * length
    j = 0
    for i in range(1, length):
        while j >= 0 and string[j] != string[i]:
            if j - 1 >= 0:
                j = border_length_prefix[j - 1]
            else:
                j = -1
        j += 1
        border_length_prefix[i] = j
    return border_length_prefix


print(get_longest_border(input())[-1])