#include <stdio.h>
#include <stdlib.h>
#include <memory.h>
#include <string>
#include <algorithm>

const char ABC[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
const int SIZE = (sizeof(ABC) - 1);

int input_num()
{
    int n = 0;
    char buff[256];
    if (fgets(buff, sizeof(buff), stdin) != 0) {
        n = atoi(buff);
    }
    return n;
}

const char *calc(const int N, std::string &buff)
{
    int n = N + 1;
    do {
        n -= 1;
        buff += ABC[n % SIZE];
        n /= SIZE;
    } while (n != 0);
    std::reverse(buff.begin(), buff.end());
    return buff.c_str();
}

int main()
{
    const int N = input_num();
    std::string buff;
    printf("%s\n", calc(N, buff));
    return 0;
}