#include<bits/stdc++.h>
using namespace std;
int main(){
	long long int n,temp;
	cin>>n;
	temp=n;
	int dig;
	string s="";
	while(n)
	{
		n=n-1;
		char a=(char)'a'+n%26;
		s=a+s;
		n=n/26;
		
		
	}
	cout<<s<<"\n";

	
	
	
	
	
	
	return 0;
}