#include<cstdio>
#include<iostream>
#include<string>
using namespace std;

int main(){
	string s;
	cin>>s;
	int one,two;
	char a[27];
	for (int i=1;i<=26;++i){
		a[i]= 'A'+i-1;
	}
	for(int i=0;i<s.length();i++){
		one=s[i]-'0';
		if(i!=s.length()-1) two=10*one+s[i+1]-'0';		
		if(two<=26&&two!=0){
			cout<<a[two];
			i++;
			two=0;
		}
		else{
			cout<<a[one];
		}
	}
	return 0;
}