#include <cstdio>

#include <cstring>

#include <algorithm>

#define M 41

#define N 100011

#define max(x, y) ((x) > (y) ? (x) : (y))

int n, m, ans, last;

struct node

{

	int sum[M], id;

	node()

	{

		id = 0;

		memset(sum, 0, sizeof(sum));

	}

}p[N];

inline bool cmp(node x, node y)

{

	int i;

	for(i = 1; i <= m; i++)

		if(x.sum[i] != y.sum[i])

			return x.sum[i] < y.sum[i];

	return x.id < y.id;

}

inline bool check(int x, int y)

{

	int i;

	for(i = 1; i <= m; i++)

		if(p[x].sum[i] != p[y].sum[i])

			return 0;

	return 1;

}

int main()

{

	int i, j, x;

	scanf("%d %d", &n, &m);

	for(i = 1; i <= n; i++)

	{

		scanf("%d", &x);

		p[i].id = i;

		for(j = 1; j <= m; j++)

			p[i].sum[j] = p[i - 1].sum[j] + bool(x & (1 << j - 1));

	}

	for(i = 1; i <= n; i++)

		for(j = 1; j <= m; j++)

			p[i].sum[j] -= p[i].sum[m];

	std::sort(p + 1, p + n + 2, cmp);

	last = p[1].id;

	for(i = 2; i <= n + 1; i++)

	{

		if(check(i, i - 1))

			ans = max(ans, p[i].id - last);

		else last = p[i].id;

	}

	printf("%d\n", ans);

	return 0;

}