#include<bits/stdc++.h>
using namespace std;
const int mx = 1e5+10;
int arr[mx];
int tree[4*mx];
void init1(int node,int b,int e)
{
    if(b==e)
    {
        tree[node] = arr[b];
        return;
    }
    int left = node * 2;
    int right = node *2+1;
    int mid = (b+e)/2;
    init1(left,b,mid);
    init1(right,mid+1,e);
    tree[node]=max(tree[left],tree[right]);
}
int query1(int node,int b,int e,int i,int j)
{
    if(i>e || j<b)
        return 0;
    if(b>=i && e<=j)
        return tree[node];
    int left = node * 2;
    int right = node * 2 + 1;
    int mid = (b+e)/2;
    int p = query1(left,b,mid,i,j);
    int q = query1(right,mid+1,e,i,j);
    return max(p,q);
}
void init(int node,int b,int e)
{
    if(b==e)
    {
        tree[node] = arr[b];
        return;
    }
    int left = node * 2;
    int right = node *2+1;
    int mid = (b+e)/2;
    init(left,b,mid);
    init(right,mid+1,e);
    tree[node]=min(tree[left],tree[right]);
}
int query2(int node,int b,int e,int i,int j)
{
    if(i>e || j<b)
        return 0;
    if(b>=i && e<=j)
        return tree[node];
    int left = node * 2;
    int right = node * 2 + 1;
    int mid = (b+e)/2;
    int p = query2(left,b,mid,i,j);
    int q = query2(right,mid+1,e,i,j);
    return min(p,q);
}
int main()
{
    int t,cnt=1;
    scanf("%d",&t);
    while(t--)
    {
        int n,d;
        scanf("%d%d",&n,&d);
        for(int i=0; i<n; i++)
            scanf("%d",&arr[i]);

        init1(1,0,n-1);
        init(1,0,n-1);
        int ans =-1;
        for(int i=0; i<=n-d; i++)
        {
            ans = max(ans,abs(query1(1,0,n-1,i,i+d-1)-query2(1,0,n-1,i,i+d-1)));
        }
        printf("Case %d: ",cnt++);
        printf("%d",ans);
    }
}