#include<bits/stdc++.h>
using namespace std;
string s,w,x="0123456789ABCDEF";
int a;
int main(){
cin>>s;
if(s.size()%4==1)s+="000";
else if(s.size()%4==2)s+="00";
else if(s.size()%4==3)s+='0';
for(int i=0;i<s.size();i+=4){
	w=s.substr(i,4);
	a=(w[0]-'0')*8+(w[1]-'0')*4+(w[2]-'0')*2+(w[3]-'0')*1;
	cout<<x[a];
	
}
	return 0;
}

/**************************************************************
	Problem: 1289
	User: wuhanyu
	Language: C++
	Result: Wrong Answer
****************************************************************/