#include<bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef pair<ll,ll> P;
typedef map<ll,ll>::iterator itll;
typedef long double ld;
typedef map<ll,ll> mapll;

#define con continue
#define pb push_back
#define fi first
#define se second
#define fr front()
#define INF 1000000000000000000
#define all(vl) vl.begin(),vl.end()
#define m_p make_pair 
#define sz(a) sizeof(a)
#define forn(mp,it) for(it = mp.begin();it!=mp.end();it++)
#define FOR(i,a,n) for(int i=a;i<n;i++) 
#define FORE(i,a,n) FOR(i,a,n+1)
#define Endl endl
#define eNdl endl
#define enDl endl
#define endL endl

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	ll k;
	cin>>k;
	vector<ll> vl;
	string s = "~abcdefghijklmnopqrstuvwxyz";
	if(k<=26)
	{
		cout<<s[k]<<endl;
		return 0;
	}
	while(k>=26)
	{
		ll yu = k%26;
		k/=26;
		if(yu == 0)
		{
			yu = 26;
			k--;
		}
		vl.pb(yu);
	}
	if(k>0)
		vl.pb(k);
	reverse(all(vl));
	FOR(i,0,vl.size())
	{
		if(vl[i]>0)cout<<s[vl[i]];
		else cout<<"z";
	}
	cout<<endl;
	return 0;
}

#include<bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef vector<ll> vi;
typedef pair<ll, ll> pi;
typedef vector<pi> vpi;
typedef vector<string> vsi;
typedef map<ll, ll> mape;
#define rep(i, a, b) for(ll i=(ll)a;i<=(ll)b;i++)
#define per(i, a, b) for(ll i=(ll)a;i>=(ll)b;i--)
#define fastio {ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);}
#define N 2100
#define MAX 1234567890
#define f first
#define s second
#define pb push_back
#define mkp make_pair
#define MOD 1000000007

int main()
{
    fastio;

    ll n;
    cin >> n;
    string s = "";
    while(n > 26){
        ll rem = n % 26;
        if(rem == 0) {
            s += 'z';
            rem = 26;
        }
        else s += ('a' + rem - 1);
        n = (n - rem) / 26;
    }
    s += ('a' + n - 1);
    reverse(s.begin(), s.end());

    cout << s << endl;

    return 0;
}
