#include<bits/stdc++.h>
using namespace std;
int main(){
long long int n;
cin>>n;
int a=0;
string s;
while(n>0){
	n=n-1;
	s+=char('a'+n%26);
	
	n=n/26;
}
int i=s.length()-1;
string s1="";
while(i>=0){
	s1+=s[i];
	i--;
	
}
cout<<s1<<endl;
  
 
}