#include <stdio.h>
#include <string.h>
#include <algorithm>
using namespace std;

double dp[2024][105];
int main() {
	int n, m;
	int i, j, k, a, b;
	double A[2024], sum[2024];
	while(scanf("%d %d", &n, &m) == 2) {
		sum[0] = 0;
		for(i = 1; i <= n; i++) {
			scanf("%lf", &A[i]);
			sum[i] = sum[i-1] + A[i];
		}
		for(int i = 0; i <= n; i++)
			for(int j = 0; j <= m; j++)
				dp[i][j] = 1e+30;
		dp[0][0] = 0;
		for(int i = 1; i <= n; i++) {
			for(int j = 1; j <= m; j++) {
				for(int k = i; k >= 1; k--) {
					dp[i][j] = min(dp[i][j], 
						dp[k-1][j-1] + (sum[i]-sum[k-1]) * i);
				}
			}
		}
		printf("%.1lf\n", dp[n][m]);
	}
	return 0;
}