#include<bits/stdc++.h>
using namespace std;
long long n;
int main(){
	cin>>n;
	n++;
	string s;
	while (n>0){
		int x=n%26;
		if(x==0){
			s+='Z';
			n=n/26-1;
		}	
		else {
			n/=26;
			s+=char(x-1+'A');
		}
	} 
	reverse(s.begin(),s.end());
	cout<<s;
	return 0;
}