#include<iostream>
using namespace std;

typedef long long ll;

int main(){
    ll n;
    cin >> n;
    string s = "";
    do{
        string append = {(char)('A' + n%26)};
        s = append + s;
        n /= 26;
    }while(n > 25);

    if(n != 0){
        string append = {(char)('A' + n - 1)};
        s = append + s;
    }

    cout << s << endl;
    return 0;
}