#include <bits/stdc++.h>
const std::vector<std::string> alphabet = {"A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z"};
std::vector<std::string> d;
void solve(long long n) {
    while (n >= 26) {
        d.push_back(alphabet[n%26]);
        n = (n / 26) - 1;
    }
    d.push_back(alphabet[n%26]);
} 

void No327() {
    using namespace std;
    long long N; cin >> N;
    solve(N);
    int n = static_cast<int>(d.size());
    for (int i = n - 1; n > 0; n--) {
        cout << d[i];
    }
    cout << endl;
}

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);
    std::cout << std::fixed << std::setprecision(10);
    std::cerr << std::fixed << std::setprecision(10);
    No327();
    return 0;
}