from collections import Counter

from icecream import ic


string: str = input()
max_weight = 0

def calculate_weight(counter: Counter[str], length: int) -> int:
    max_occurence: int = counter.most_common(1)[0][1]
    return max_occurence * length

counter: Counter[str] = Counter()

for length in range(1, len(string) + 1):
    counter.clear()
    counter.update(
        string[i:i+length] for i in range(len(string) - length + 1)
    )
    # ic(counter)
    max_weight: int = max(
        max_weight,
        calculate_weight(counter, length)
    )
    ic(max_weight)

print(max_weight)