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

string f(int n) {
    string res;
    while (n) {
        n--; // 从1开始计数，所以先减1
        res= char('A' + n % 26) + res;
        n /= 26;
    }
    return res;
}

int main() {
    int n = 2019;
    cout << f(n) << endl;
    return 0;
}