import java.util.Arrays;
import java.util.Scanner;
 
 
public class Main{
    public static void main(String[] args){
        int n,i,j,k,temp,b;
        long ans=0,x;
        Integer c[];
        Scanner sc = new Scanner(System.in);
        n=sc.nextInt();
        x=sc.nextLong();
        c=new Integer[n];
        for(i=0;i<n;i++)
        {
            c[i]=sc.nextInt();
        }
        Arrays.sort(c);
 
        for(j=0;j<n;j++,x--)
        {
                if(x<1)x=1;
                ans=ans+c[j]*x;
            }
        System.out.println(ans);
        }
 
    }

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