AT_abc171_c

#include <iostream>
#include <stack>
#define int long long
using namespace std;
char a[30],x='a';
int n;
stack <char> st;
signed main(){
	for(int i=1;i<=26;++i){
		a[i]=x;
		x++;
	}
	cin>>n;
	while(n>26){
		st.push(a[n%26]);
		n/=26;
	}
	st.push(a[n%26]);
	while(!st.empty()){
		cout<<st.top();
		st.pop();
	}
	return 0;
}