#include <bits/stdc++.h>

using namespace std;

#define INF 2000000000
#define MOD 1000000007
typedef long long ll;
typedef pair<int, int> P;


int main()
{
	ll n;
	cin >> n;
	vector<ll> a;

	while (true) {
		ll tmp = n % 26;
		a.push_back(tmp);
		n -= 26;
		if (n<0) {
			break;
		}
	}
	string alpha = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
	for (int i = 0; i < a.size(); i++) {
		cout << alpha[a[i]];
	}
	cout << "\n";
}