include <bits/stdc++.h>

using namespace std; string s="0123456789ABCDEF",str,ans; int main() {

while (cin>>str && str!="0")
{
	ans="";
	int len=str.length();
	for (int i=len-1; i>=0; i-=4)
	{
		int t=0;
		t+=str[i]+(str[i-1])*2+(str[i-2])*4+(str[i-3])*8;
		ans+=s[t%16]; 
	}
	reverse(ans.begin(),ans.end());
	cout<<ans<<"\n";
}
return 0;

}