#include <bits/stdc++.h>
#include <iostream>
using namespace std;

int main() {
	long long n;
	cin >> n;
	string name = "";
	while (1) {
		n--;
		name += (n % 26 + 'a');
		n /= 26;
		if (n == 0) break;
	}
	reverse(name.begin(), name.end());
	cout << name;
}

#include<stdio.h>
#define ll long long

int main()
{
	ll n, j = 0;
	char str[255];
	
	scanf("%lld", &n);
	
	while(n != 0){
		--n;
		str[j++] = n % 26 + 'a';
		n /= 26;
	}
	for(int i = j - 1; i >= 0; i--){
		printf("%c", str[i]);
	}
}