#include <iostream>
#include <string>
#include <algorithm>
#include <functional>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <bitset>
#include <map>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
using namespace std;
typedef long long ll;
typedef pair<int,int> pint;
typedef vector<int> vint;
typedef vector<pint> vpint;
#define mp make_pair
#define fi first
#define se second
#define all(v) (v).begin(),(v).end()
#define rep(i,n) for(ll i=0;i<(n);i++)
#define reps(i,f,n) for(int i=(f);i<(n);i++)

int main(void){
	ll n; cin >> n;
	vector<char> ans;
	ll syou = n / 26;
	ll amari = n % 26;
	//printf("%lld %lld\n", syou, amari);
	ans.push_back('A' + amari);

	while(syou != 0){
		ll tmp = syou;
		syou /= 26;
		amari = tmp % 26;
		//printf("%lld\n", amari);
		if(amari == 0) ans.push_back('Z');
		else ans.push_back('A' + amari - 1);
	}
	reverse(all(ans));
	rep(i, ans.size()) printf("%c", ans[i]);
	printf("\n");
	return 0;

	

}