#include <stdio.h>
#include <string.h>
int main(){
    long long n;
    if(scanf("%lld", &n) != 1){
        printf("Invalid input");
        return 0;
    }
    if(n <= 0){
        printf("+1");
        return 0;
    }
    char result [50];
    int idx = 0;
    if (n == 0){
        printf("Invalid input");
        return 0;
    }
    while(n > 0){
        long long re = (n - 1) % 26;
        result[idx++] = 'A' + rem;
        n = (n - 1) / 26;
    }
    result[idx] = '\0';
    for (int i = 0; i < idx/2; i++){
        char temp = result[i];
        result[i] = result[idx - 1 - i];
        result[idx - 1 i] = temp;
    }
    printf("%s", result);
    return 0;
}