#include<iostream>
using namespace std;
long long n,a,b,s,ans,t,nn[1000000];
int main(){
	cin>>n;
	n+=1;
	ans=n;
	if(ans==0)cout<<'A';
	for(long long i=ans;i>0;i/=26){
		if(i%26==0){
			nn[t++]=26;
			i--;
			continue;
		}
		nn[t++]=i%26;
	}
	for(int i=t-1;i>-1;i--){
		if(nn[i]<=25)cout<<char('A'+nn[i]-1);
		else cout<<'Z';
	}
	cout<<endl;
	return 0;
}