1 #pragma comment(linker, "/STACK:102400000,102400000")
 2 #include <cstdio>
 3 #include <iostream>
 4 #include <cstdlib>
 5 #include <cstring>
 6 #include <algorithm>
 7 #include <cmath>
 8 #include <cctype>
 9 #include <map>
10 #include <set>
11 #include <queue>
12 #include <bitset>
13 #include <string>
14 #include <complex>
15 #define ll __int64
16 #define mod 1000000007
17 using namespace std;
18 int t;
19 int n,m;
20 int a[10004];
21 int dp[5005][10004];
22 int q[10004],head,tail;
23 int main()
24 {
25     scanf("%d",&t);
26     for(int s=1; s<=t; s++)
27     {
28         scanf("%d %d",&n,&m);
29         for(int j=1; j<=n; j++)
30             scanf("%d",&a[j]);
31         sort(a+1,a+1+n);
32         for(int j=1; j<=n; j++)
33             dp[1][j]=(a[j]-a[1])*(a[j]-a[1]);
34         for(int i=2; i<=m; i++)
35         {
36             head=tail=0;
37             q[tail++]=i-1;
38             for(int j=i; j<=n; j++)
39             {
40                 while(head+1<tail)
41                 {
42                     int p1=q[head],p2=q[head+1];
43                     int x1=a[p1+1],x2=a[p2+1];
44                     int y1=dp[i-1][p1]+x1*x1,y2=dp[i-1][p2]+x2*x2;
45                     if(y2-y1<2*a[j]*(x2-x1))
46                         head++;
47                     else
48                         break;
49                 }
50                 int k=q[head];
51                 dp[i][j]=dp[i-1][k]+(a[j]-a[k+1])*(a[j]-a[k+1]);
52                 while(head+1<tail&&j!=n)
53                 {
54                     int p1=q[tail-2],p2=q[tail-1],p3=j;
55                     int x1=a[p1+1],x2=a[p2+1],x3=a[p3+1];
56                     int y1=dp[i-1][p1]+x1*x1,y2=dp[i-1][p2]+x2*x2,y3=dp[i-1][p3]+x3*x3;
57                     if((y3-y2)*(x2-x1)<=(y2-y1)*(x3-x2))
58                         tail--;
59                     else
60                         break;
61                 }
62                 q[tail++]=j;
63             }
64         }
65         printf("Case %d: %d\n",s,dp[m][n]);
66     }
67     return 0;
68 }