#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);
}



void solve() {
	ll n;
	cin >> n;
	string ans = "";
	while (n >= 0){
		ans = (char)('A' + (n % 26)) + ans;
		n /= 26;
		n--;
	}
	cout << ans << endl;
}

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