#include <bits/stdc++.h>
using namespace std;
int arr[100000],m,n,maxx=-1;
void gcd(int ans,int k,int m,int l){
	if(l==n+1){
		maxx=max(ans,maxx);
		return;
	}
	if(arr[l]==k){
		ans++;
	}
	l++;
	if(m==0){
		gcd(ans,k,m,l);
	}else{
		if(k==1){
			gcd(ans,2,m-1,l);
			gcd(ans,1,m,l);
		}else if(k==2){
			gcd(ans,1,m-1,l);
			gcd(ans,2,m,l);
		}
	}
}
int main(){
	ios::sync_with_stdio(false);
	cin.tie(0),cout.tie(0);
	int k;
	cin>>n>>m;
	for(int i=1;i<=n;i++){
		cin>>arr[i];
	}
	gcd(0,1,m,1);
	cout<<maxx;
}

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

NyAyCjIKMQoxCjIKMgoxCjE=

7 2
2
1
1
2
2
1
1