#include <fstream>
#include <string>
using namespace std;

string ASCII_to_Base64(string s);

string Base64_to_ASCII(string s);

int main()
{
   ifstream fin ("base64.in");
   ofstream fout ("base64.out");
   
   char c, cer = fin.get();
   fin.get();

   string s, ans;
   while ((c = fin.get()) != -1)
      s.push_back(c);

   if (cer == '1')
      ans = ASCII_to_Base64(s);
   else if (cer == '2')
      ans = Base64_to_ASCII(s);

   fout << ans;
}