[백준] 1235 python

n = int(input())
k = 1

numbers = []
for i in range(n):
  numbers.append(input())

while(True):
  new = []
  for i in range(n):
    num  = numbers[i][-k:]
    # print(num, new)
    if num not in new:
      new.append(num)
    else:
      continue
  if len(new) == n:
    break
  k += 1

print(k)