#include <iostream>

using namespace std;

const int N = 1e6 + 1;

int n, first[N], mx = 1;

int main() {
// 	freopen("input.txt", "r", stdin);
// 	freopen("output.txt", "w", stdout);

	cin >> n;
	for (int i = 0; i < N; ++i)
		first[i] = -1;

	for (int a, i = 0; i < n; ++i) {
		cin >> a;

		a += 5e5;

		if (first[a] == -1) {
			first[a] = i;
		}
		else {
			mx = max(mx, i - first[a] + 1);
		}
	}

	cout << mx << endl;
}