#include<bits/stdc++.h>
using namespace std;
using ll=long long;

int main(){
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  int N,M;
  cin>>N>>M;
  vector A(N,0ll);
  for(ll &i:A)cin>>i;
  sort(A.begin(),A.end());
  ll now=0;
  for(int i=0;i<M-1;i++){
    now+=(A[i+1]-A[i])*(A[i+1]-A[i]);
  }
  ll ans=now;
  for(int i=M-1;i<N-1;i++){
    now+=(A[i+1]-A[i])*(A[i+1]-A[i])-(A[i-M+2]-A[i-M+1])*(A[i-M+2]-A[i-M+1]);
    ans=min(ans,now);
  }
  cout<<ans<<'\n';
}