#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll, ll> l_l;
typedef pair<int , int> i_i;
typedef vector<ll> vl;
typedef vector<int> vi;
typedef vector<char> vec;
typedef vector<bool> veb;
typedef vector<string> ves;
typedef vector<vector<ll>> vvl;
typedef vector<vector<int>> vvi;
typedef vector<vector<char>> vvec;
typedef vector<vector<bool>> vveb;
typedef vector<vector<string>> vves;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define rep1(i,n) for(int i=1;i<(int)(n);i++)
#define rep2(i,n) for(int i=2;i<(int)(n);i++)
#define repk(i,k,n) for(int i=k;i<(int)(n);i++)
#define rev(v) reverse(v.begin(), v.end())
#define fs first
#define sc second
#define pb push_back
#define pp pop_back
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define maxel(a) *max_element(all(a))
#define minel(a) *min_element(all(a))
#define acc accumulate
#define EPS (1e-7)
#define INF (1e9)
#define PI (acos(-1))
#define mod (1000000007)
typedef long long int64;
//const int64 INF = 1LL << 58;
#define dame { puts("-1"); return 0;}
#define YES { cout << "YES" << endl; return 0; }
#define NO { cout << "NO" << endl; return 0; }
#define Yes { cout << "Yes" << endl; return 0; }
#define No { cout << "No" << endl; return 0; }
#define OK { cout << "OK" << endl; return 0; }
#define NG { cout << "NG" << endl; return 0; }
#define sz(v) ((int)(v).size())
#define uniq(a) sort(all(a));(a).resize(unique(all(a)) - a.begin());
#define dab(v) for(auto i:v)cout<<i<<' '; cout << endl;
#define vin(v) for (ll i = 0; i < v.size(); ++i) cin >> v[i];
template<class T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }
template<class T>void out(T a){cout << a << endl;}
template<class T>void die(T a){cout << a << endl; exit(0);}
int dx[] = {0, 0, -1, 1};
int dy[] = {1, -1, 0, 0};

#define SIZE 200005
#define MOD 1000000007
 
typedef pair <int,int> P;
 
ll inv[SIZE], fac[SIZE], finv[SIZE];
void make(){
	fac[0] = fac[1] = 1;
	finv[0] = finv[1] = 1;
	inv[1] = 1;
	for(int i=2; i<SIZE; i++)
	{
		inv[i] = MOD - inv[MOD%i]*(MOD/i)%MOD;
		fac[i] = fac[i-1] * (ll) i % MOD;
		finv[i] = finv[i-1] * inv[i] % MOD;
	}
    return ;
}
ll comb(int a,int b){
	if(a < b) return 0;
	return fac[a] * (finv[b] * finv[a-b] % MOD) % MOD;
}



ll beki(int a, int n){
    if(n == 0) return 1;
    ll ans = beki(a, n / 2);
    ans = ans * ans;
    if(n % 2 == 1) ans = ans * a;
    return ans;
}

class Radix {
private:
  const char* s;
  int a[128];
public:
  Radix(const char* s = "0123456789ABCDEF") : s(s) {
    int i;
    for(i = 0; s[i]; ++i)
      a[(int)s[i]] = i;
  }
  string to(long long p, int q) {
    int i;
    if(!p)
      return "0";
    char t[64] = { };
    for(i = 62; p; --i) {
      t[i] = s[p % q];
      p /= q;
    }
    return string(t + i + 1);
  }
  string to(const string& t, int p, int q) {
    return to(to(t, p), q);
  }
  long long to(const string& t, int p) {
    int i;
    long long sm = a[(int)t[0]];
    for(i = 1; i < (int)t.length(); ++i)
      sm = sm * p + a[(int)t[i]];
    return sm;
  }
};



int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);
    //cout << fixed << setprecision(15);
    
  ll N; cin>>N;
  string ans;
  while(N > 0){
    N -= 1;
    ans+= (char)('a' + N % 26);
    N /= 26;
  }
  reverse(all(ans));
  out(ans);
	
}

Measured memory_bytes: 3636