#include "stdio.h"

#include "stdlib.h"

#define maxn 100000

#define maxm 500

int dp[maxn + 1][maxm + 2][2];

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

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

int main() {

int n, m, d;

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

scanf("%d", &d);

dp[1][1][1] = d;

for (int i = 2; i <= n; i++) {

scanf("%d", &d);

int mm = min(i, m);

for (int j = 0; j <= mm; j++) {

dp[i][j][0] = max(dp[i - 1][j + 1][0], dp[i - 1][j + 1][1]);

if (j == 0) dp[i][j][0] = max(dp[i][j][0], dp[i - 1][0][0]);

if (j - 1 > 0)

dp[i][j][1] = d + dp[i - 1][j - 1][1];

else if (j - 1 == 0)

dp[i][j][1] = d + dp[i - 1][0][0];

}

}

printf("%d", dp[n][0][0]);

return 0;

}