#include<cstdio>
#include<cstring>
#include<iostream>
using namespace std;
const int MAXL = 100005;
char str[MAXL];
int main()
{
    int T, k;
    scanf("%d",&T);
    getchar();
    for (int t = 1; t <= T; t++)
    {
        gets(str);
        scanf("%d", &k);
        getchar();
        printf("Case #%d:\n", t);
        int len = strlen(str);
        int r = len / k;
        int c = len % k;
        int iter = 0, pos = 0;
        for(;;)
        {
            for (int i = 0; i < k; i++)
            {
                printf("%c", str[pos]);
                iter++;
                if (iter >= len)
                    goto a;
                if (i < c)
                    pos += (r + 1);
                else
                    pos += r;
                if (pos >= len)
                    pos = pos % len + 1;
            }
        }
        a:
        printf("\n");
    }
    return 0;
}