#include <iostream>

using namespace std;

int n, ap[500000], an[500000];
int a1[500000], a2[500000];
bool rep = 0;
int main(){
// 	freopen("input.txt", "r", stdin);
// 	freopen("output.txt", "w", stdout);

	int ans = 0;
	cin >> n;

	for (int i = 1; i <= n; ++i)
	{
		int x;
		cin >> x;
		if (x >= 0)
		{
			if (ap[x] > 0)
			{
				a1[x] = i - ap[x];
			}else{
				ap[x] = i;
			}
		}else{
			x = -x;
			if (an[x] > 0)
			{
				a2[x] = i - an[x];
			}else{
				an[x] = i;
			}
		}


	}
	if (an[500000] == 1)
	{
		cout << 1;
		return 0;
	}

	int mx1 = 0;
	for (int i = 0; i <= 500000; ++i)
	{
		//cout << a1[i] << endl;
		mx1 = max(mx1, a1[i]);
	}
	int mx2 = 0;
	for (int i = 0; i <= 500000; ++i)
	{
		// cout << a2[i] << endl;
		mx2 = max(mx2, a2[i]);
	}

	cout << max(mx1, mx2) + 1;
	






	return 0;

}