#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<cctype>
#include<cmath>
#include<iostream>
#include<sstream>
#include<iterator>
#include<algorithm>
#include<string>
#include<vector>
#include<set>
#include<map>
#include<stack>
#include<deque>
#include<queue>
#include<list>
#define lowbit(x) (x & (-x))
const double eps = 1e-8;
inline int dcmp(double a, double b){if(fabs(a - b) < eps) return 0;return a > b ? 1 : -1;
}
typedef long long LL;
typedef unsigned long long ULL;
const int INT_INF = 0x3f3f3f3f;
const int INT_M_INF = 0x7f7f7f7f;
const LL LL_INF = 0x3f3f3f3f3f3f3f3f;
const LL LL_M_INF = 0x7f7f7f7f7f7f7f7f;
const int dr[] = {0, 0, -1, 1, -1, -1, 1, 1};
const int dc[] = {-1, 1, 0, 0, -1, 1, -1, 1};
const int MOD = 1e9 + 7;
const double pi = acos(-1.0);
const int MAXN = 1000 + 10;
const int MAXT = 10000 + 10;
using namespace std;
int dp[MAXN][35][3];
int a[MAXN];
int Move(int k){return k == 1 ? 2 : 1;
}
int main(){int T, W;scanf("%d%d", &T, &W);for(int i = 1; i <= T; ++i){scanf("%d", &a[i]);}if(a[1] == 1){dp[1][0][1] = 1;}else{dp[1][1][2] = 1;}for(int i = 1; i <= T - 1; ++i){for(int j = 0; j <= W; ++j){for(int k = 1; k <= 2; ++k){if(k == a[i + 1]){dp[i + 1][j][k] = max(dp[i + 1][j][k], dp[i][j][k] + 1);dp[i + 1][j + 1][Move(k)] = max(dp[i + 1][j + 1][Move(k)], dp[i][j][k]);}else{dp[i + 1][j + 1][Move(k)] = max(dp[i + 1][j + 1][Move(k)], dp[i][j][k] + 1);dp[i + 1][j][k] = max(dp[i + 1][j][k], dp[i][j][k]);}}}}int ans = 0;for(int i = 0; i <= W; ++i){for(int j = 1; j <= 2; ++j){ans = max(ans, dp[T][i][j]);}}printf("%d\n", ans);return 0;
}