/*
 * this is the program which  
 * convert NUM to STRING
 * 
 *     0  ...  25    
 *     A  ...   Z    
 * 
 *    26  ...  51  <-- INPUT
 *    AA  ...  AZ  <-- OUTPUT
 * 
 *    ..  ...  ..
 * 
 *   676  ... 701
 *    ZA  ...  ZZ
 *
 *   702  ...
 *   AAA  ...
 */


#include<stdio.h>
#include<string.h>

void loop(long n)
{
    if (n>25){
        loop(n/26-1);
        printf("%c",'A'+n%26);
    }else 
        printf("%c",'A'+n);
}

int main( )
{
    long n;
    scanf("%ld",&n);
    loop(n);
    printf("\n");
    
    return 0;
}