#include <cstdio>
#include <cstring>
#include <iostream>

using namespace std;
const int oo = 1000000007;
const int N = 1e5+10;
typedef long long llg;
char s[N],a[N];
int main()
{
    int cas;
    scanf("%d",&cas);
    for(int _=1;_<=cas;_++)
    {
        scanf(" ");
        gets(s);
        int len = strlen(s);
        int n;
        scanf("%d",&n);
        int k = len % n;
        int p = len / n + 1;
        //if(p*n<=len) p++;
        int top = 0;
        for(int i=0;i<p;i++)
        {
            int id = i;
            for(int j=0;j<n;j++)
            {
                if(id>=len ||top>=len) break;
                a[top++] = s[id];
                id += (p-(j>=k));
            }
        }
        a[top] = 0;
        printf("Case #%d:\n%s\n",_,a);
    }
    return 0;
}