#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<cmath>
#include<string>
using namespace std;
const int maxn=10010;
const int N=10;
char s[500001];
int main(){
int n;
cin>>n;
int len=0;
for(int i=1;i<=n;i++){
strcat(s+len+1,s);
s[len]='A'+i-1;
len=len*2+1//len=strlen(s); 降低时间复杂度
}
printf("%s\n",s);
return 0;
}