#include<bits/stdc++.h>
using namespace std;
char zimu(int n){
	return n + 64;
}
int main(){
   string a[26];
   int i = 0,n;
   cin>>n;
   for(i = 1;i <= n;i++){
   	  if(i == 1){
   	     a[i] = "A";	
	  }else{
	  	 a[i] = a[i - 1] + zimu(i) +a[i - 1];
	  }
   }
   cout<<a[n];
   return 0;
}

/**************************************************************
	Problem: 1474
	User: admin
	Language: C++
	Result: Accepted
	Time:22 ms
	Memory:2076 kb
****************************************************************/