#include <bits/stdc++.h>
using namespace std;

int main(){
	long long n;
	cin >> n;
	string str = "";
	while(n >= 26){
		int mod = n % 26;
		str += char('A' + mod);
		n = (n - 26) / 26;
	}
	str += char('A' + n);
	reverse(str.begin(),str.end());
	cout << str << endl;
	return 0;
}