#include <iostream>

#include <vector>

#include <algorithm>

using namespace std;

int main(){

    long long n,x;

    cin >> n >> x;

    vector<long long> c(n);

    for(int i =  ; i < n; ++ i) cin >> c[i];

    sort(c.begin(),c.end());

    long long res = ;

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

        res +=c[i]*(x>  ? x--: );

    }

    cout<<res<<endl;

}