#include <bits/stdc++.h>
typedef  long long ll;
#define INF 1000000000
using namespace std;
#define N 1000000
#define MOD 1000000007
int main(void){
    ll n;
    cin>>n; 
    int num_a=n/26;
    int last_c=n%26;
    string ans;
    for(int i=0;i<num_a;i++){
        ans.push_back('A');
    }
    ans.push_back('A'+last_c);
    cout<<ans<<endl;
}