import collections

n = int(input())
s_list = [input() for i in range(n)]

max_freq = -1
max_key = -1
s_clc = collections.Counter(s_list)

for key in s_clc.keys():
    if s_clc[key] > max_freq:
        max_freq = s_clc[key]
        max_key = len(key)
    elif s_clc[key] == max_freq and len(key) > max_key:
        max_key = len(key)
    
print(max_key - 2)