#include <iostream>
#include <string>
#include <algorithm>
#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);
	}

	unordered_map<int, int> foundNumbers;
	int maxCount = 0;
	int j = 0;
	for (int i = 0; i < N; i++)
	{
		int num = buffer[i];
		if (foundNumbers.count(num) == 0) {
			foundNumbers[num] = 0;
		}
		else {
			maxCount = max(maxCount, i - j);
			while (true) {
				foundNumbers.erase(buffer[j]);
				if (buffer[j] == buffer[i])
					break;
				j++;
			}
			foundNumbers[num] = 0;
			j++;
		}
	}
	
	maxCount = max(maxCount, (int)foundNumbers.size());
	cout << maxCount << endl;

	return 0;
}