#include <iostream>
#include <vector>
#include <set>
#include <cmath>
#include <algorithm>
#include <string>
using namespace std;
typedef long long ll;
#define rep(i,n) for (int i = 0; i < (n); ++i)

int main(){
    ll N;
    cin >> N;
    ll N_ = N;
    string ans="";

    char tmp = 'A'+N_%26;
    ans += tmp;
    N_ /= 26;
    while(N_){
        N_--;
        int s = N_ % 26;
        tmp = 'A' + s;
        ans += tmp;
        N_ /= 26;
    }
    cout << ans << endl;
}