//
// File:   encr.cc
// Author: cteam007
//
// Created on October 22, 2011, 4:54 PM
//

#include <stdlib.h>
#include <string>
#include <iostream>

using namespace std;

//
//
//
int main(int argc, char** argv) {
    
    string puvodni;
    char* vysledek;
    char znak;
    char dummy;
//nacteni kroku
    unsigned int krok;
    unsigned int pocatek;
   unsigned int index;
    unsigned int praindex;
    
    while(1) {
    scanf("%d", &krok);
    if(!krok) return 0;
    scanf("%c", &dummy);
    
    //nacteni znaku-nacteme cely radek
    while(1){
        scanf("%c", &znak);
        if(znak=='\n') break;
        if(znak==' ') continue;
        puvodni+=znak;
    }
    
    //cout<<puvodni<<endl;
    
    vysledek=new char[puvodni.size()];
    pocatek=0;
    index=0;
    praindex=0;
    while(pocatek<krok && pocatek<puvodni.size()){
        //cout<<"beru znak z pozice "<<
        //if(puvodni[praindex]==' '){
        //    praindex++;
        //    continue;
       // }
          
        vysledek[pocatek+index*krok]=puvodni[praindex];
        if(puvodni[praindex]>'Z')  vysledek[pocatek+index*krok]+=('A'-'a');
        index++;
        praindex++;
        if((pocatek+index*krok)>=puvodni.size()){
            index=0;
            pocatek++;
        }
        //cout<<"index, pocatek "<<index<<" "<<pocatek<<endl;
        
    }
    for(unsigned int i=0; i<puvodni.size(); i++){
        cout<<vysledek[i];
    }
    cout<<endl;
    
    puvodni.clear();
    delete [] vysledek;
    }
    
    return (0);
}