#include<iostream>
#include<cmath>

using namespace std;

const int N = 1e5 + 10;
int sum[N];
typedef pair<int, int> PII;
PII q[2 * N + 10];

int main()
{
	int n;
	cin >> n;
	for (int i = 1; i <= n; i++)
	{
		int t;
		cin >> t;
		if (t == 0) t = -1;
		sum[i] += sum[i - 1] + t;
		q[sum[i] + N].second = i;
		if (q[sum[i] + N].first == 0) q[sum[i] + N].first = i;
	}
	int ans = 0;
	for (int i = 0; i < 2 * N + 10; i++)
	{
		ans = max(ans, q[i].second - q[i].first);
	}
	cout <<  ans;
	return 0;
}