#include <cstdio>

#include <cmath>

#include <cstring>

#include <iostream>

#include <algorithm>

#include <queue>

#include <vector>

#include <map>



using namespace std;



typedef long long LL;


int T,k;
int n,m;
int len,num;
char s[100005];
char c;
vector<char> f[100005];
int main()

{
    scanf("%d",&T);gets(s);
    for (int z=1;z<=T;++z)
    {
        gets(s);
        len=strlen(s);
        scanf("%d",&k);
        printf("Case #%d:\n",z);
        n=(len-1)/k+1;
        m=(len-1)%k+1;
        num=0;
        for (int i=1;i<=n;++i)
        {
            f[i].clear();
            for (int j=1;j<=k+1;++j) f[i].push_back('0');
        }
        for (int i=1;i<=m;++i)
            for (int j=1;j<=n;++j)
            {
                f[j][i]=s[num];
                num++;
            }
        for (int i=m+1;i<=k;++i)
            for (int j=1;j<n;++j)
            {
                f[j][i]=s[num];
                num++;
            }
        for (int i=1;i<n;++i)
        {
            for (int j=1;j<=k;++j) cout<<f[i][j];
        }
        for (int i=1;i<=m;++i) cout<<f[n][i];
        cout<<endl;
        gets(s);
    }

    return 0;

}