#include <map>
#include <set>
#include <list>
#include <deque>
#include <queue>
#include <cmath>
#include <stack>
#include <string>
#include <vector>
#include <cctype>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <utility>
#include <iostream>
#include <iterator>
#include <algorithm>
using namespace std;
#define REP(i, n) for(int i = 0; i < n; ++i)
#define REP1(i, a, n) for(int i = a; i <= n; ++i)
#define REPD(i, n) for(int i = n; i >= 0; --i)
#define clm(m, a) memset(m, a, sizeof(m))
#define e  2.71828182845904523536
#define PI 3.14159265358979323846
#define exp 1e-9
#define fi first
#define se second
typedef long long ll;
typedef unsigned long long llu;
typedef pair<int, int> pii;
char s[1000000];
char d[100];
int key;
int main()
{
#ifdef LOCAL
freopen("in","r",stdin);
#endif
    int cases, caseno = 0;
    scanf("%d", &cases);
    gets(d);
    while(cases--) {
        gets(s);
        scanf("%d", &key);
        gets(d);
        int len =strlen(s);
        int divi = len / key;
        int mo = len % key;
        int m = divi + ((len%key) ? 1 : 0);
        printf("Case #%d:\n", ++caseno);
        int cur = 0;
        REP(i, m) {
            int j = i, tot = 0;
            if(cur++ < len) printf("%c", s[j]);
            while(j+m < len && tot < mo) {j += m; if(cur++ < len) printf("%c", s[j]); tot++;}
            while(j+divi < len) {j += divi; if(cur++ < len) printf("%c", s[j]);}
        }
        printf("\n");
    }
    return 0;
}