// 
// File:   encipher.cc
// Author: cteam003
//
// Created on October 22, 2011, 2:24 PM
//

#include <stdlib.h>
#include <stdio.h>

//
// 
//
int main(int argc, char** argv) {
    int N;
    char pole[10001];
    char upper[10001];
    int i, j, step;
    while (42){
        i=0;
        j=0;
        scanf ("%d",&N);
        if (N==0)return 0;
        gets(pole);
        while (pole[i]!='\0'){
            if (pole[i]>'Z'){
                upper[j]=pole[i]-32;
                j++;
            }
            else if (pole [i]!=' ') {
                upper[j]=pole[i];
                j++;
            }
            i++;
        }
        step=1;
        i=0;
        for (int k=0; k<j; k++){
            pole[i]=upper[k];
            i+=N;
            if (i>=j) i=step++;
        }
        pole[j]='\0';
        printf("%s\n",pole);
    }    
    return (EXIT_SUCCESS);
}