#include <iostream>
#include <cstring>
#include <cmath>
#include <cstdio>
#include <algorithm>
using namespace std;
#define N 100050
char ch[N];int sg[N],n,m,t;
inline int Read()
 {
     int x=0;char y;
     do y=getchar(); while (y<'0'||y>'9');
     do x=x*10+y-'0',y=getchar(); while (y>='0'&&y<='9');
     return x;
 }

int main()
 {
     //freopen("input.txt","r",stdin);
     t=Read();
     for (int T=1;T<=t;T++)
      {
          gets(ch+1);n=Read();m=strlen(ch+1);int Now=true;
          for (int i=1;i<=m;i++)
           {
               sg[Now]=i;Now+=n;
               if (Now>m) Now=Now%n+1;
           }
          printf("Case #%d:\n",T);
          for (int i=1;i<=m;i++) putchar(ch[sg[i]]);
          puts("");
      }
     return 0;
 }