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

using namespace std;


int main()
{
    for (int i = 1; i <= 26; i ++ )
       for (int j = 1; j < 26; j ++ )
          for (int k = 1; k < 26; k ++ )
          {
              int cal=i+26*j+26*26*k;
              if(cal==2021)
              {
                  printf("%c%c%c",'A'-1+k,'A'-1+j,'A'-1+i);
                  break;
              }
          }



    return 0;
}