#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <string>
#include <cmath>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <cstring>

typedef long long ll;
using namespace std;

#define mod 1000003
#define INF 1000000000
#define LLINF 2000000000000000000LL

#define SIZE 100

string ans;

int add(int n,char a,char b){
    ll i,c,C;
    
    
    ans+=a;
    
    if(n<4)
        return n-1;
    
    ans+=b;
    ans+=a;
    
    if(n<9)
        return n-4;
    
    i=2;
    c=4;
    
    while(1){
        C = ((i+1)*i)/2+((i-1)*i)/2+i+1+i;
        
        if(C > (ll)n){
            return n-(int)c;
        }
        
        ans+=b;
        ans+=a;
        
        c = C;
        i++;
    }
    
}

int main(){
    int n;
    
    scanf("%d",&n);
    
    for(int i=0;;i+=2){
        
        n = add(n,'a'+i%26,'a'+(i+1)%26);
        
        if(n==0){
            cout << ans << endl;
            return 0;
        }
        
    }
    
    return 0;
}