tyvj1125 JR's chop

//chopsticks弱化版

#include<iostream>
#include<cstdio>
#include<string>
#include<cstring>
#include<algorithm>
using namespace std;
int m,n,a[5005];
long long dp[1005][5005];
int main(){
    cin>>n>>m;
    for(int i = n;i >= 1;i--){
        scanf("%d",&a[i]);
    }
    sort(a+1,a+1+n);
    m += 3;
    for(int i = 1;i <= m;i++){
        for(int j = 1;j <= n;j++){
            if(j < i * 2) dp[i][j] = 9876543212345L;
            else dp[i][j] = min(dp[i][j-1],dp[i-1][j-2] + (a[j] - a[j-1]) * (a[j] - a[j-1]));
        }
    }
    cout<<(dp[m][n] == 9876543212345L ? -1 : dp[m][n]);
    return 0;
}