#include<bits/stdc++.h>
using namespace std;
int main(){
  char s[26];
  int i=0;
  for(char c='A';c<='Z';c++){
    s[i]=c;
    i++;
  }
  int in;
  cin>>in;
  for(int i=0;i<in/26;i++){
    cout<<s[in%26];
  }
  cout<<s[in%26]<<endl;
  return 0;
}