#include <iostream>
#include <string>
#include <fstream>
using namespace std;

string imenakol(int i) {
	i--;
	string s = "";
	s += (char)('A' + (i % 26));

	if ((i = i / 26) > 0)
	{
		s = imenakol(i) + s;
	}
	return s;
}
int main()
{
        ifstream in;
        in.open("excel.in");
        ofstream out;
        out.open("excel.out");
        long long cisl;
        in  >> cisl;
		out << imenakol(cisl) << endl;

	return 0;
}