#include <bits/stdc++.h>
#include <iostream>
#include <math.h>
using namespace std;
int main() {
    int N;
    cin >> N;
    string ans = "";
    while (N > 0) {
        N--;
        ans += (char)('a' + N % 26);
        N /= 26;
    }

    reverse(ans.begin(), ans.end());
    cout << ans << endl;
    return 0;
}