#include <iostream>
#include <string>
#include <algorithm>
#include <cstring>

#pragma warning (disable:4996)

using namespace std;

char s[100005];

int main() {
    int t, cas = 1;
    cin >> t;
    cin.get();
    while (t--) {
        int k, n;    
        gets(s);
        cin >> k;
        cin.get();
        n = strlen(s);
        int a, b;
        a = (n + k - 1) / k;
        b = n % k;
        b = (b == 0 ? k : b);
        cout << "Case #" << cas++ << ":\n";
        for (int i = 0; i < a; i++) {
            int j = i;
            int d = b;
            while (j < n) {
                cout << s[j];
                j += a - (d > 0 ? 0 : 1);
                d--;
                if (i == a - 1) {
                    if (d <= 0) break;
                }
            }
        }
        cout << endl;
    }
    return 0;
}