#include <cstdio>
#include <algorithm>
int n,k,now,tmp,len;
int s[100050][30],a[100050];
void work(int pos,int u) {
	for (int i = 1;i <= k;i++) {
		if (u & 1) s[pos][i] = s[pos - 1][i] + 1;
		else s[pos][i] = s[pos - 1][i];
		u >>= 1;
	}
}

int main() {
	freopen("balline.in","r",stdin);
	freopen("balline.out","w",stdout);
	scanf("%d %d",&n,&k);
	now = 0;
	len = 0;
	for (int i = 1;i <= n;i++) {
		scanf("%d",&a[i]);
		work(i,a[i]);
	}
	bool ok;
	for (int len = n;len >= 1;len--) 
		for (int i = 1;i <= n - len + 1;i++) {
			int j = i + len - 1;
			ok = 1;
			for (int u = 1;u < k;u++) if (s[j][u] - s[i - 1][u] != s[j][u + 1] - s[i - 1][u + 1]) {
				ok = 0;
				break;
			}
			if (ok) {
				printf("%d",len);
				return 0;
			}
		}
	printf("%d",0);
	return 0;
}