#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <string>
#include <queue>
#include <stack>
#include <math.h>
#include <set>
#include <cstdio>
#define ALL(obj) (obj).begin(),(obj).end()
#define RALL(obj) (obj).rbegin(),(obj).rend()
#define P pair<int, int>

#define MOD 1000000007
#define INF 1012345678
#define NINF (-2147483647-1)
#define LLINF 9223372036854775807
using ll = long long;
using namespace std;

int main() {
    ll N;
    string S;
    cin >> N;
    if (N == 0) {
        cout << "A" << endl;
    }
    else {
        bool b = false;
        while (N) {
            if (b) {
                S.push_back(char('A' - 1 + N % 26));
            }
            else {
                S.push_back(char('A' + N % 26));
            }
            N /= 26;
            b = true;
        }
    }
    for (int i = S.length() - 1; i >= 0; i--)
    {
        cout << S[i];
    }
    cout << endl;
    getchar(); getchar();
}