#include <iostream>
#include <string>
#include <unordered_map>

using namespace std;

int main() {
	int N;
	cin >> N;

	int* buffer = new int[N];
	for (int i = 0; i < N; i++) {
		string A;
		cin >> A;
		buffer[i] = stoi(A);
	}

	int maxCount = 0;
	int count = 0;
	unordered_map<int, int> foundNumbers;
	for (int index = 0; index < N; index++)
	{
		int num = buffer[index];
		if (foundNumbers.find(num) == foundNumbers.end()) {
			foundNumbers[num] = index;
			count++;
		}
		else {
			if (maxCount < count)
				maxCount = count;
			int matchedNumIndex = foundNumbers[num];
			count = index - matchedNumIndex;
			foundNumbers[num] = index;

			for (int i = 0; i < matchedNumIndex; i++) {
				if (buffer[i] != num)
					foundNumbers.erase(buffer[i]);
			}
		}
	}
	
	if (maxCount < count)
		maxCount = count;

	cout << maxCount << endl;

	return 0;
}