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