#include <iostream>
#include <vector>
#define pr(s) std::cout << s << std::endl
using namespace std;
int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	long long n;
	cin >> n;
	vector<char> c;
	vector<char>::iterator it = c.begin();
	c.insert(it, n % 26 + 'A');
	it = c.begin();
	n /= 26;
	int t;
	while (n) {
		if ((t = n % 26) == 0) {
			c.insert(it, 'Z');
		}
		else {
			c.insert(it, t + 'A' - 1);
		}
		it = c.begin();
		n /= 26;
	}
	if (*it == 'A' && *(it + 1) == 'Z') {
		++it;
	}
	while (it != c.end()) {
		cout << *it;
		++it;
	}
	cout << endl;
}