void main(){
  import std.stdio, std.string, std.conv, std.algorithm;
  import std.array;

  int n; rd(n);
  
  char[] s=['a'];
  int k=1;
  while(k<n){
    if(k*2<=n){
      s=s[0]~s~s[$-1];
      k*=2;
    }else{
      for(char c='a'; c<='z'; c++){
        if(c!=s[0]){s=c~s~c; break;}
      }
      k+=1;
    }
  }

  writeln(s);
}


void rd(T...)(ref T x){
  import std.stdio, std.string, std.conv;
  auto l=readln.split;
  assert(l.length==x.length);
  foreach(i, ref e; x){
    e=l[i].to!(typeof(e));
  }
}