#include <algorithm>
#include <iostream>
#include <iomanip>
#include <map>
#include <numeric>
#include <set>
#include <sstream>
#include <string>
#include <vector>
#include <cmath>
using namespace std;

#define FOR(i,s,e) for (int i = int(s); i != int(e); i++)
#define FORIT(i,c) for (typeof((c).begin()) i = (c).begin(); i != (c).end(); i++)
#define ISEQ(c) (c).begin(), (c).end()

int main(){
    long N;
    cin >>  N;
    string s = "";
    N++;
    while(N!=0){
    	N--;
    	char c = 'A' + N%26;
    	s = s +  c;
    	N/=26;
    }


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