#include <bits/stdc++.h>
using namespace std;
#define MODS 100005
#define MOD 1000000007
#define all(x) (x).begin(), (x).end()
#define ll long long int
#define ld long double
#define bigint int64_t
#define vll vector<ll>
#define vpll vector<pair<ll,ll>>
#define mp make_pair
#define pb push_back
#define test ll t;read(t);while(t--)
#define pll pair<ll,ll>
#define vvll vector<vector<ll>>
#define fst first
#define scd second
#define ins insert
#define line "\n"
string yes="YES";
string no="NO";

#define forn(i,n) for(ll (i) = 0 ; (i) < (n) ; ++(i))
#define for1(i,n) for(ll (i) = 1 ; (i) <= (n) ; ++(i))
#define forr(i,n) for(ll (i) = (n)-1 ; (i)>=0 ; --(i))
#define forab(i,a,b,c) for(ll (i) = a ; (i) <= (b) ; (i)+=(c))

template <typename T>
void read(T &x){
    cin >> x;
}
template <typename T , typename T0>
void read(T &x,T0 &y){
    cin >> x >> y;
}

template <typename T , typename T0 , typename T1>
void read(T &x,T0 &y,T1 &z){
    cin >> x >> y >> z;
}

template <typename T , typename T0 , typename T1 , typename T2>
void read(T &x,T0 &y,T1 &z,T2 &w){
    cin >> x >> y >> z >> w;
}

template <typename T , typename T0>
void read(pair< T , T0 > &p){
    cin >> p.fst >>p.scd;
}

template <typename T>
void read(vector< T > &oneD,ll n){
    forn(i,n)
    {
        ll x;
        read(x);
        oneD.push_back(x);
    }
}

template <typename T>
void read(T oneD[] , ll n){
    for(ll i=0;i<n;i++){
        read(oneD[i]);
    }
}

template <typename T>
void write(T &x){

    cout << x << " ";
}

template <typename T>
void wrtline(T &x){

    cout << x << line;
}

template <typename T , typename T0>
void write(T &x,T0 &y){
    cout << x << " " << y << "\n";
}

template <typename T , typename T0 , typename T1>
void write(T &x,T0 &y,T1 &z){
    cout << x << " " << y << " " << z << "\n";
}

template <typename T , typename T0 , typename T1 , typename T2>
void write(T &x,T0 &y,T1 &z,T2 &w){
    cout << x << " " << y << " " << z << " " << w << "\n";
}

template <typename T , typename T0>
void write(pair< T , T0 > &p){
    write(p.fst);
    write(p.scd);
    cout << line;
}

template <typename T>
void write(vector< T > &oneD,ll n){
    for(ll i=0;i<n;i++){
        cout<<oneD[i]<<" ";
    }
    cout << line;
}

template <typename T>
void write(T oneD[] ,int n){
    for(ll i=0;i<n;i++){
        write(oneD[i]);
    }
    cout <<line;
}

template <typename T , typename T0>
void write(map< T , T0 > &mpp){
    for(auto it : mpp){
        write(it.fst);
        cout << ": ";
        write(it.scd);
        cout << "\n";
    }
    cout<<line;
}
void write(vvll rc,ll n,ll m)
{
    forn(i,n)
    {
        forn(j,m)
        {
            cout<<rc[i][j]<<" ";
        }
        cout<<line;
    }
}

ll modularExponentiation(ll x,ll n)
{
    ll result=1;
    while(n>0)
    {
        if(n % 2 ==1)
            result=(result * x);
        x=(x*x);
        n=n/2;
    }
    return result;
}

void solve()
{
    ll n;
    read(n);
    ll i=26;
    ll dsum=1,usum=26;
    ll x=0;
    while(usum<n)
    {
        dsum+=i;
        usum+=(i*26);
        i*=26;
        x++;
    }
//    write(dsum,usum);
    ll d;
    if(x==0)
        d=1;
    else
    {
        forn(i,x)
        {
            d=modularExponentiation(26,x);
        }
    }
//    wrtline(d);
    for(ll i=d;i>0;i/=26)
    {
        ll ch=0;
        ll flag=0;
//        write(dsum,usum);
        forab(j,dsum,usum,i)
        {
            if(j>n)
            {
                dsum=j-i;
                usum=j;
                flag=1;
                break;
            }
            ch++;
        }
        if(flag==0)
        {
            dsum=usum-i+1;
        }
//        cout<<ch<<line;
        cout<<(char)(ch+96);
//        cout<<i<<line<<line;
    }
}
int main() {
    /*#ifndef ONLINE_JUDGE
         freopen("input.txt", "r", stdin);
         freopen("output.txt", "w", stdout);
     #endif*/
ios_base::sync_with_stdio(false);
cin.tie(NULL);
//*******************************************************//
/*test*/
solve();

return 0;
}


Measured memory_bytes: 3644