#define _USE_MATH_DEFINES
#define _CRT_SECURE_NO_WARNINGS
#include "bits/stdc++.h"
#define rep(i,n) for(int i = 0;i < n;i++)
#define REP(i,n,k) for(int i = n;i < k;i++)
#define P(p) cout<<(p)<<endl;
#define pi 3.1415926535
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
int dx[] = { 0, 1, 0, -1 };
int dy[] = { -1, 0, 1, 0 };

unsigned long long sttoi(std::string str) {
	unsigned long long ret;
	std::stringstream ss; ss << str;
	ss >> ret;
	return ret;
}

ll gcd(ll a, ll b){
	if (b > a)swap(a, b);
	if (b == 0) return a;
	return gcd(b, a%b);
}
ull L[] = { 0, 26, 676, 17576, 456976, 11881376, 308915776, 8031810176 };

void solve() {
	ull n;
	cin >> n;
	string ans = "";
	int p, length = 0;
	for (int i = 0; i < 8; i++){
		if (n >= L[i]){
			ans = ans + "A";
			length++;
		}
	}
	while (n > 0){
		for (int i = 0; i < 8; i++){
			if (n >= L[i]){
				p = i;
			}
		}
		if (p == 0){
			ans[0] = (char)('A' + n);
			n = 0;
		}
		else{
			ans[p] = (char)('A' + (n / L[p]));
			n -= L[p] * (n / L[p]);
		}
	}
	for (int i = length - 1; i >= 0; i--){
		cout << ans[i];
	}
	cout << endl;
}

int main() {
	solve();
	return 0;
}