import java.util.Scanner;
import java.util.Arrays;
 
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; // 需要保留的歌曲数量
 
        if (m == 0) {
            System.out.println(0);
            return;
        }
 
        long[] a = new long[n];
        for (int i = 0; i < n; i++) {
            a[i] = scanner.nextLong();
        }
 
        // dp[i][j] 表示前i首歌中保留j首的最小等待时间
        long[][] dp = new long[n+1][m+1];
        for (long[] row : dp) {
            Arrays.fill(row, Long.MAX_VALUE);
        }
        dp[0][0] = 0;
 
        for (int i = 1; i <= n; i++) {
            for (int j = 0; j <= Math.min(i, m); j++) {
                // 不选当前歌曲
                if (dp[i-1][j] != Long.MAX_VALUE) {
                    dp[i][j] = dp[i-1][j];
                }
                // 选当前歌曲
                if (j > 0 && dp[i-1][j-1] != Long.MAX_VALUE) {
                    long newVal = dp[i-1][j-1] + (j-1) * a[i-1];
                    if (newVal < dp[i][j]) {
                        dp[i][j] = newVal;
                    }
                }
            }
        }
 
        System.out.println(dp[n][m]);
    }
}

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