#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <algorithm>
#include <iostream>
#include <queue>
#include <stack>
#include <vector>
#include <map>
#include <set>
#include <string>
#include <math.h>
using namespace std;
#pragma warning(disable:4996)
#pragma comment(linker, "/STACK:1024000000,1024000000")
typedef long long LL;
const int INF = 1 << 30;
/**/
const int N = 1000 + 10;
struct Node
{int id, height;bool operator <(const Node &rhs){return height < rhs.height;}
}a[N];
struct Edge
{int v, dist;Edge(){}Edge(int _v, int _dist) :v(_v), dist(_dist){}bool operator<(const Edge&rhs)const{return dist > rhs.dist;}
};
vector<Edge> g[N];
int dist[N];
bool vis[N];
int dij(int x, int y, int n)
{for (int i = 1; i <= n; ++i)dist[i] = INF;priority_queue<Edge> q;Edge cur, tmp;cur.dist = dist[x] = 0;cur.v = x;q.push(cur);while (!q.empty()){cur = q.top(); q.pop();int u = cur.v;if (dist[u] < cur.dist)//如果cur.dist < dist[u]， 那么可以继续更新其他顶点， 代替了条件vis[u]continue;for (int i = 0; i < g[u].size(); ++i){int v = g[u][i].v;if (dist[v] > dist[u] + g[u][i].dist){tmp.dist = dist[v] = dist[u]+ g[u][i].dist;tmp.v = v;q.push(tmp);}}}return dist[y];
}int spfa(int x, int y, int n)
{for (int i = 1; i <= n; ++i)dist[i] = INF;queue<int> q;q.push(x);dist[x] = 0;while (!q.empty()){int u = q.front(); q.pop();vis[u] = false;for (int i = 0; i < g[u].size(); ++i){int v = g[u][i].v;if (dist[v] > dist[u] + g[u][i].dist){dist[v] = dist[u] + g[u][i].dist;//能更新就更新if (!vis[v])//如果结点在队里里面，就不用重复入队了
                {q.push(v);vis[v] = true;}}}}return dist[y];
}
int main()
{int n, d, t;scanf("%d", &t);for (int k = 1; k <= t; ++k){scanf("%d%d", &n, &d);for (int i = 1; i <= n; ++i)g[i].clear();for (int i = 1; i <= n; ++i){scanf("%d", &a[i].height);a[i].id = i;if (i != 1)g[i].push_back(Edge(i-1, -1));}sort(a + 1, a + n + 1);bool flag = true;for (int i = 2; i <= n; ++i){if (abs(a[i].id - a[i - 1].id) > d){flag = false;break;}g[min(a[i].id, a[i - 1].id)].push_back(Edge(max(a[i].id, a[i - 1].id), d));}printf("Case %d: ", k);if (!flag)puts("-1");else{if (a[1].id > a[n].id)swap(a[1].id, a[n].id);printf("%d\n", spfa(a[1].id, a[n].id,n));}}return 0;
}