#include <bits/stdc++.h>
using namespace std;
#define GET_MACRO(_1, _2, _3, NAME, ...) NAME
#define _repl(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
#define _rep(i,n) _repl(i,0,n)
#define rep(...) GET_MACRO(__VA_ARGS__, _repl, _rep)(__VA_ARGS__)
#define mp(a,b) make_pair((a),(b))
#define pb(a) push_back((a))
#define all(x) (x).begin(),(x).end()
#define uniq(x) sort(all(x)),(x).erase(unique(all(x)),end(x))
#define fi first
#define se second
#define dbg(...) _dbg(#__VA_ARGS__, __VA_ARGS__)
void _dbg(string){cout<<endl;}
template<class H,class... T> void _dbg(string s,H h,T... t){int l=s.find(',');cout<<s.substr(0,l)<<" = "<<h<<", ";_dbg(s.substr(l+1),t...);}
template<class T,class U> ostream& operator<<(ostream &o, const pair<T,U> &p){o<<"("<<p.fi<<","<<p.se<<")";return o;}
template<class T> ostream& operator<<(ostream &o, const vector<T> &v){o<<"[";for(T t:v){o<<t<<",";}o<<"]";return o;}

#define INF 1120000000
#define MOD 1000000007

#define LEN 200
class RollingHash {
private:
  static const long B1 = 10007, B2 = 10009;
  static const long MD1 = 1000000007, MD2 = 1000000009;
  static long pow1[], pow2[];
public:
  static void initHash(){
    pow1[0]=1;
    rep(i,LEN+4) pow1[i+1] = pow1[i]*B1 % MD1;
    pow2[0]=1;
    rep(i,LEN+4) pow2[i+1] = pow2[i]*B2 % MD2;
  }
  long h1[LEN+5], h2[LEN+5];
  int n;
  string &s;
  RollingHash(string &str) : s(str){
    if(pow1[0] == 0 || pow2[0]==0) initHash();
    n = s.size();
    assert(n<=LEN);
    h1[0] = h2[0] = s[0];
    rep(i,1,n){
      h1[i] = (h1[i-1]*B1 + s[i])%MD1;
      h2[i] = (h2[i-1]*B2 + s[i])%MD2;
    }
  }
  pair<long,long> get(int from, int l){
    if(l == 0) return mp(0L,0L);
    if(from == 0) return mp(h1[l-1], h2[l-1]);
    long ret1 = (h1[from+l-1] - h1[from-1]*pow1[l])%MD1;
    if(ret1<0) ret1 += MD1;
    long ret2 = (h2[from+l-1] - h2[from-1]*pow2[l])%MD2;
    if(ret2<0) ret2 += MD2;
    return mp(ret1, ret2);
  }
};
long RollingHash::pow1[LEN+5], RollingHash::pow2[LEN+5];

// long dp[LEN][LEN];
long dp[LEN];

int check(string &s){
  int n = s.size();
  RollingHash hash(s);
  fill(dp, dp + n+1, 0);
  int l=0,r=n;
  while(l<=r){
    dp[l] = 1;
    l++; r--;
  }
  l--;r++;
  while(l>=0){
    for(int d=1; l-d>=0; d++){
      if(hash.get(l-d, d) == hash.get(r, d)){
        (dp[l-d] += dp[l]) %= MOD;
      }
    }
    l--;r++;
  }

  return dp[0];
}

int main(){
  int n;
  cin>>n;
  int m = n;

  string s;
  int c = 0;
  while(n>1){
    s +='a'+c;
    if(n%2==1 && n!=1){
      c = (c+1)%26;
      s += 'a'+c;
    }
    n /= 2;
  }

  string t(s);
  reverse(all(t));
  s = s + t;

  if(s.size()==0) s = "a";

  cout << s << endl;
  // dbg(check(s));
  assert(check(s) == m);
}