n = int(input()) if n == 0: print(0) else: a = list(map(int, input().split())) last_occurrence = {} max_length = 0 left = 0 for right in range(n): current = a[right] if current in last_occurrence and last_occurrence[current] >= left: left = last_occurrence[current] + 1 last_occurrence[current] = right current_length = right - left + 1 if current_length > max_length: max_length = current_length print(max_length)