#define _USE_MATH_DEFINES
#include<stdio.h>
#include<string>
#include<iostream>
#include<cctype>
#include<cstdio>
#include<vector>
#include<stack>
#include<queue>
#include <algorithm>
#include<math.h>
#include<set>
#include<map>
#include<iomanip>

//#include<bits/stdc++.h>



using namespace std;




int main() {
	
	long long int n;
	cin>>n;
	string a="";
	
	do{
		int p;
		
		if(a.size()){n--;p=n%26;n/=26;}//p--;
		else {p=n%26;n/=26;}
		a+='A'+p;
		//n/=26;
	}while(n);
	reverse(a.begin(),a.end());
	cout<<a<<endl;
	return 0;
}