#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <string>
#include <map>
#include <stack>
#include <vector>
#include <set>
#include <queue>
#define maxn 205
#define MAXN 100005
#define mod 100000000
#define INF 0x3f3f3f3f
#define pi acos(-1.0)
#define eps 1e-6
typedef long long ll;
using namespace std;

int n,m,ans,cnt,tot,flag;
int a[10005],dp[2][10005];
int q[10005];

int sqr(int x)
{
    return x*x;
}
int get(int i,int k)
{
    return dp[i][k]+a[k+1]*a[k+1];
}
void solve()
{
    int i,j,t,dx1,dy1,dx2,dy2,k1,k2,turn=0;
    int head,tail;
    sort(a+1,a+n+1);
    memset(dp,0x3f,sizeof(dp));
    dp[0][0]=0;
    for(i=1; i<=m; i++)
    {
        head=0; tail=-1;
        q[++tail]=i-1;
        for(j=i; j<=n; j++)
        {
            while(head<tail) // 将不再更新答案的点删除
            {
                k1=q[head+1];
                k2=q[head];
                dx1=a[k1+1]-a[k2+1];
                dy1=get(turn,k1)-get(turn,k2);
                if(dy1<=dx1*2*a[j]) head++;
                else break ;
            }
            dp[turn^1][j]=dp[turn][q[head]]+sqr(a[j]-a[q[head]+1]);
            while(head<tail) // 维护下凸曲线
            {
                dx1=a[j+1]-a[q[tail]+1];
                dy1=get(turn,j)-get(turn,q[tail]);
                dx2=a[q[tail]+1]-a[q[tail-1]+1];
                dy2=get(turn,q[tail])-get(turn,q[tail-1]);
                if(dy1*dx2<=dy2*dx1) tail--;
                else break ;
            }
            q[++tail]=j;
        }
        turn^=1;
    }
    ans=dp[turn][n];
}
int main()
{
    int i,j,t,test=0;
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d%d",&n,&m);
        for(i=1; i<=n; i++)
        {
            scanf("%d",&a[i]);
        }
        solve();
        printf("Case %d: %d\n",++test,ans);
    }
    return 0;
}