#include <stdio.h>

int arr[1000];
int d[1000];

int max(int a, int b) { return a < b ? b : a; }

int main()
{
	int n;
	scanf("%d", &n);
	for (int i = 0; i < n; ++i)
	{
		scanf("%d", arr + i);
		if (arr[i] < 0) arr[i] *= -1;

		++d[arr[i]];
	}

	int res = 0;
	for (int i = 1; i <= 100; ++i)
	{
		res = max(res, d[i] + d[i - 1]);
	}

	printf("%d\n", res);
	return 0;
}