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