#include<bits/stdc++.h>
using namespace std;
long long n; 
string s = "";
int main(){
    cin >> n;
    n++;
    while(n > 0){
        int t = n % 26;
        if(t == 0) s += 'Z',n = n / 26 - 1;
        else s += char(t + 64),n = n / 26;
	}
	for(int i = s.size() - 1;i >= 0;i--){
		cout << s[i];
	}
	cout << endl;
	return 0;
}