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

#define MAX_TITLE_LEN 10
void reverseString(char *str){
    int length = strlen(str);
    char *start = str;
    char *end = str + length -1;
    while(start < end){
        char temp = *start;
        *start = *end;
        *end = temp;
        start++;
        end--;
    }
}

int main(){
    char inputBuffer[20];
    long n_long;
    int n;
    char *endptr;
    
    if(fgets(inputBuffer,sizeof(inputBuffer),stdin) == NULL){
        printf("Invalid input");
        return 1;
    } 
    
    inputBuffer[strcspn(inputBuffer,"\n")]=0;
    
    n_long = strtol(inputBuffer,&endptr,10);
    
    if(endptr == inputBuffer || *endptr != '\0'){
        printf("Invalid input");
        return 0;
    }
    
    if(n_long <=0 || n_long > INT_MAX){
        printf("Invalid input");
        return 0;
    }
    
    n = (int)n_long;
    char title[MAX_TITLE_LEN];
    int i = 0;
    
    while (n>0){
        int remainder = (n-1)%26;
        
        title[i++] = 'A'+remainder;
        
        n = (n-1)/26;
        
    }
    
    title[i]='\0';
    
    reverseString(title);
    printf("%s",title);
    
    return 0;
    }