#include<iostream>
#include<cstdio>
#include<vector>
#include<sstream>
#include<cstring>
#include<vector>
#define mem(a,x) memset(a,x,sizeof(a))
using namespace std;
const int N = 100010;
char s[N];
vector<char>G[N];
int main(){
    int t;scanf("%d",&t);
    for(int cas=1;cas<=t;cas++){
        printf("Case #%d:\n",cas);
        getchar();
        gets(s);

        int len  = strlen(s);
        int key; scanf("%d",&key);
        int rear = len % key;
        int remain = len / key;
        int cc = 0;
        for(int i=0;i<remain+1;i++)
            G[i].clear();
        if(rear == 0){
            for(int i=0;i<key;i++){
                for(int j=0;j<remain;j++){
                    G[j].push_back(s[cc++]);
                }
            }
        }
        else{
            remain ++;
            for(int i=0;i<key;i++){
                for(int j=0;j<remain;j++){
                    G[j].push_back(s[cc++]);
                }
                rear--;
                if(rear == 0)
                    remain--;
            }
            //cout<<cc<<endl;
            remain++;
        }
        for(int i=0;i<remain;i++){
            for(int j=0;j<G[i].size();j++){
                printf("%c",G[i][j]);
            }
        }
        printf("\n");
    }
    return 0;
}