#include<bits/stdc++.h>
using namespace std;
long long n;
int main(){
    cin >> n;
    long long s = 0;
    while(n > 0){
    	s *= 10;
    	s += n % 26;
    	n /= 26;
	}
	string c = "";
    while(s >= 26){
    	int t = s % 26;
    	char e = t + 65;
    	c += e;
    	s /= 26;
	}
	char e = s + 65;
	c += e;
	for(int i = c.size() - 1;i >= 0;i--){
		cout << c[i]; 
	}
	return 0;
}