#pragma region template 2.4
#include <bits/stdc++.h>
using namespace std;
template <typename T>
using pq_asc = priority_queue<T, vector<T>, greater<T>>;
typedef long long ll;
typedef vector<ll> vi;
typedef vector<vi> vvi;
typedef pair<ll, ll> ii;
typedef vector<ii> vii;
typedef vector<string> vs;
#define REP(i, n) for (ll i = 0; i < (n); ++i)
#define REP1(i, n) for (ll i = 1; i <= (n); ++i)
#define FOR(i, a) for (auto &i : a)
#define CH(f, x, y) x = f(x, y)
#define IN(T, x) \
    T x;         \
    cin >> x;
#define AIN(T, a, n) \
    vector<T> a(n);  \
    FOR(i, a)        \
    cin >> i;
#define A2IN(T1, a, T2, b, n) \
    vector<T1> a(n);          \
    vector<T2> b(n);          \
    REP(i, n)                 \
    cin >> a[i] >> b[i];
#define OUT(x) cout << (x) << endl;
#define FOUT(x) cout << fixed << setprecision(15) << (x) << endl;
#define ALL(a) (a).begin(), (a).end()
#define SORT(a) sort(ALL(a))
#define RSORT(a) \
    SORT(a);     \
    reverse(ALL(a))
#define DUMP(x) cout << #x << " = " << (x) << endl;
#define DUMPA(a)          \
    cout << #a << " = {"; \
    JOUT(ALL(a), ", ", cout) << "}" << endl;

template <typename T>
ostream &JOUT(T s, T e, string sep = " ", ostream &os = cout)
{
    if (s != e)
    {
        os << *s;
        ++s;
    }
    while (s != e)
    {
        os << sep << *s;
        ++s;
    }
    return os;
}

ostream &YES(bool cond, string yes = "Yes", string no = "No", ostream &os = cout)
{
    if (cond)
    {
        os << yes << endl;
    }
    else
    {
        os << no << endl;
    }
    return os;
}

template <typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p)
{
    os << '(' << p.first << ", " << p.second << ')';
    return os;
}

template <typename T>
ostream &operator<<(ostream &os, const vector<T> &v)
{
    os << '[';
    JOUT(ALL(v), ", ", os) << ']';
    return os;
}

const ll INF = 1e18;
const ll MOD = 1e9 + 7;
#pragma endregion template

int main()
{
    IN(ll, N);
    --N;
    string ans;
    ans.push_back('a' + N % 26);
    N /= 26;
    while (N > 0)
    {
        ans.insert(ans.begin(), 'a' + N % 26);
        N /= 26;
    }
    // DUMP(ans);
    ll M = ans.size();
    for (ll i = M - 2; i >= 1; --i)
    {
        if (ans[i] == 'a')
        {
            ll j = i;
            for (; ans[j] == 'a'; --j)
            {
                ans[j] += 25;
            }
            --ans[j];
        }
        else
        {
            --ans[i];
        }
    }
    if (M >= 2)
    {
        if (ans[0] == 'a')
        {
            ans.erase(ans.begin());
        }
        else
        {
            --ans[0];
        }
    }
    OUT(ans);
    // REP1(i, 2000)
    // {
    //     ll N = i;
    //     --N;
    //     string ans;
    //     ans.push_back('a' + N % 26);
    //     N /= 26;
    //     while (N > 0)
    //     {
    //         if (N % 26 == 0)
    //         {
    //             ans.insert(ans.begin(), 'z');
    //             if (N == 26)
    //             {
    //                 break;
    //             }
    //         }
    //         else
    //         {
    //             ans.insert(ans.begin(), 'a' + N % 26 - 1);
    //         }
    //         N /= 26;
    //     }
    //     OUT(ans);
    // }
}

Measured memory_bytes: 3564