#include <bits/stdc++.h>
//#include "atcoder/all"
typedef long long int ll;
using namespace std;
// using namespace atcoder;
int main() {
    ll n;
    cin >> n;
    n++;
    vector<int> ans;
    while (n) {
        if (n % 26 == 0) {
            ans.push_back(26);
            n -= 26;
        }
        else {
            ans.push_back(n % 26);
        }
        n /= 26;
    }
    for (int i = ans.size() - 1; i >= 0; i--) {
        printf("%c",'A' - 1 + ans[i]);
    }
    cout << endl;
    return 0;
}