#include<bits/stdc++.h>
using namespace std;
using ll = long long int;
ll n;
string k;
void displ()
{
	cin>>n;
	while(n){
		k = char(n%26?(n%26)+'a'-1:'z')+k,n--;
	    	n/=26;
	}
	cout<<k<<"\n";
}

int main()
{
	displ();
}