#include <bits/stdc++.h>
using namespace std;

int main() {
	// your code goes here
	long long int n;
	cin>>n;
	string s;
	while(n>0)
	{
	    n--;
	    s+=char('a'+n%26);
	    n=n/26;
	}
	reverse(s.begin(),s.end());
	cout<<s;
	return 0;
}
