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

		}
	}
	reverse(s.begin(),s.end());
	cout<<s;
	return 0;
}