import java.util.Scanner;
 
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int k = scanner.nextInt();
        int m = n - k;
        if (m == 0) {
            System.out.println(0);
            return;
        }
        long[] a = new long[n];
        for (int i = 0; i < n; i++) {
            a[i] = scanner.nextLong();
        }
        long[] dp = new long[m + 1];
        for (int j = 0; j <= m; j++) {
            dp[j] = Long.MAX_VALUE;
        }
        dp[0] = 0;
        for (int i = 0; i < n; i++) {
            long current = a[i];
            int maxJ = Math.min(m, i + 1);
            for (int j = maxJ; j >= 1; j--) {
                if (dp[j - 1] != Long.MAX_VALUE) {
                    long temp = dp[j - 1] + (m - j) * current;
                    if (temp < dp[j]) {
                        dp[j] = temp;
                    }
                }
            }
        }
        System.out.println(dp[m]);
    }
}