#include<bits/stdc++.h>
const int maxn = 1e5+50;
typedef long long LL;
LL T,n,k;
LL a[maxn];
int main ()
{
    int ic = 0;
    scanf("%lld",&T);
    while(T--)
    {
        LL sum = 0,ans = 0;
        scanf("%lld%lld",&n,&k);
        for(int i = 1;i <= n;i++)
        {
            scanf("%lld",&a[i]);
            sum += a[i];
        }
        if(sum % k)
        {
           printf("Case #%d: -1\n",++ic);
        }
        else
        {
            sum /= k;
            for(int i = 1;i <= n;i++)
            {
                if(a[i]==sum||!a[i])
                    continue;
                if(a[i]>sum)
                {
                    ans++;
                    a[i]-=sum;
                    i--;
                }
                else
                {
                    a[i+1]+=a[i];
                    a[i]=0;
                    ans++;
                }
            }
            printf("Case #%d: %lld\n",++ic,ans);
        }
        
    }
    return 0;
}