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

	return 0;
}