#include <iostream>
#include <cstdio>
#include <string>
#include <cstring>
#define LL long long
using namespace std;;
const int N = 1e5 + 10;
char s[N];
int c[N];

int main() {
    int m, kase = 1, T;
    scanf("%d%*c", &T);
    while (T--) {
        gets(s);
        scanf("%d%*c", &m);
        int l = strlen(s);
        int n = l / m + 1, t = l % m;
        for (int i = 0; i < m; ++i)
            c[i] = n - 1;
        for (int i = 0; i < t; ++i)
            c[i]++;
        char a[n + 10][m + 10];
        memset(a, 0, sizeof a);
        int cur = 0;
        for (int j = 0; j < m; ++j)
            for (int i = 0; i < c[j]; ++i)
                a[i][j] = s[cur++];
        printf("Case #%d:\n", kase++);
        for (int i = 0; i < n; ++i)
            printf("%s", a[i]);
        puts("");
    }
    return 0;
}