#include<iostream>=
#include<string>

using namespace std;

int main(){

	long long N;
	long long waru=1;
	string ans="";

	cin>>N;

	if(N==0){cout<<"A"<<endl;return 0;}
	while(N!=0) ans=(char)(N%26+'A')+ans,N/=26;

	int kuri=1;
	string sans="";
	sans+=ans[ans.size()-1];
	for(int i=ans.size()-2;i>=0;i--){
		if(ans[i]-kuri-'A'<0){
			if(i==0) break;
			sans=(char)('Z'+1+ans[i]-kuri-'A')+sans;
			kuri=2;
		}
		else{
			sans=(char)(ans[i]-kuri)+sans;
			kuri=1;
		}
	}
	cout<<sans<<endl;
}