#include <iostream>
#include <cstdint>
#include <cmath>

using namespace std;

int main() {

    ios::sync_with_stdio(false);
    cin.tie(0);

    uint64_t n;
    cin >> n;
    int ketaCounter = 1;
    for (uint64_t i = 1; (uint64_t)pow(26, i) <= n; ++i) {
        ketaCounter++;
    }
    for (int j = ketaCounter - 1; j >= 0; --j) {
        if (n >= 26) {
            cout << (char)(n / (uint64_t)pow(26, j) + 64);
        } else {
            cout << (char)(n / (uint64_t)pow(26, j) + 65);
        }
        n -= (n / (uint64_t)pow(26, j)) * (uint64_t)pow(26, j);
    }
    cout << endl;
    return 0;
}