#include <stdio.h>
#include <string.h>
#define N 100001
int main(void) {
    char in[N];
    char out[N];
    int i,j,l,cnt;
    int t,k,len,row,rem;
    scanf("%d",&t);getchar();
    for(l=1;l<=t;++l){
        gets(in);
        scanf("%d",&k);getchar();
        len = strlen(in);
        rem = len % k;
        if (rem==0) rem = k;
        row = (len + k - 1)/k;
        cnt = 0;
        for(i=0;i<k;i++){
            for(j=0;j<(i<rem?row:row-1);j++){
                out[i+j*k]=in[cnt++];
            }
        }
        out[cnt]='\0';
        printf("Case #%d:\n%s\n",l,out);
    }
    return 0;
}