bfm/.bn,nbffbkklbqq

#include<bits/stdc++.h>
using namespace std;
string s;
string t="0123456789ABCDEF";
int x;

int  main() {
	while(cin>> s)
{
	if(s.size() == 1 && s[0] == '0')break;
	   	if(s.size()%4==1) s="000"+s;
    	else if(s.size()%4==2) s="00"+s;
    	else if(s.size()%4==3) s="0"+s;
    	for(int i=0; i<s.size(); i=i+4) {
        	x=(s[i]-'0')*8+(s[i+1]-'0')*4+(s[i+2]-'0')*2+(s[i+3]-'0')*1;
        	cout<<t[x];
   }
   cout<<endl; 
	}
	return 0;
}

`