#include <iostream>
#include <string>
#include <algorithm>

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

const char *calc(const long long N, std::string &buff)
{
    long long 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()
{
    long long N;
    std::string buff;
    std::cin >> N;
    std::cout << calc(N, buff) << std::endl;
    return 0;
}