#include <iostream>
#include <sstream>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <cctype>
#include <string>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <algorithm>
using namespace std;

#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define FOR2(i,a,b) for (int i = (a); i > (b); ++i)
#define DEBUG(x) cout << '>' << #x << ':' << x << endl;
inline bool EQ(double a, double b) { return fabs(a-b) < 1e-9; }

const int INF = 1<<29;
typedef long long ll;
//////////////////////////////////////////////////////////////////////////////

char input[10047];
pair<int, char> res[10047];
int len;

int main()
{
	while (1)
	{
		int N;
		scanf("%d ", &N);
		if (!N) break;
		
		gets(input);
		len = strlen(input);
		
		int len2 = 0;
		FOR(i, 0, len)
			if (input[i] != ' ')
				input[len2++] = toupper(input[i]);
		input[len2] = 0;
		
		int index = 0;
		FOR(i, 0, N)
		{
			for (int j = i; j < len2; j += N)
			{
				res[j].first = j;
				res[j].second = input[index];
				++index;
			}
		}
		sort(res, res+len2);
		
		FOR(i, 0, len2) input[i] = res[i].second;
		printf("%s\n", input);
	}
	return 0;
}