#include <bits/stdc++.h>
#define Hoshimachi signed
#define Suisei main
using namespace std;
#define int long long
#define pii pair<int,int>
const int N=2e5+5;
int n,k;
int a[N],b[N];
pii dp[N];
pii ss(pii a, pii b){
    if(a.first!=b.first) return min(a,b);
    return max(a,b);
}
Hoshimachi Suisei(){
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    // freopen(".inp", "r", stdin);
    // freopen(".out", "w", stdout);
    cin>>n>>k;
    for(int i=1; i<=n; i++){
        cin>>a[i];
    }
    sort(a+1,a+1+n);
    for(int i=1; i<n; i++){
        b[i]=(a[i+1]-a[i])*(a[i+1]-a[i]);
    }
    int lo=-1e14,hi=1e14,mid,kq=0;
    int ans=0;
    while(lo<=hi){
        mid=(lo+hi)/2;
        dp[0]={0,0};
        for(int i=1; i<n; i++){
            pii opt=dp[i-1];
            pii nval=i==1?pii(b[1]-mid,1LL):pii(dp[i-2].first+b[i]-mid,dp[i-2].second+1);
            opt=ss(opt,nval);
            dp[i]=opt;
        }
        if(dp[n-1].second>=k){
            hi=mid-1;
            ans=dp[n-1].first;
            kq=mid;
        }
        else{
            lo=mid+1;
        }
    }
    cout<<ans+kq*k;
}