#include<bits/stdc++.h>
using namespace std;
int main()
{
	string s1,s2;
	string pos="0123456789ABCDEF";
	cin>>s1;
	int k=0,t=0;
	for(int i=s1.length()-1;i>=0;i--)
	{
		t+=(s1[i]-'0')*pow(2,k);
		if(k==3)
		{
			s2=pos[t]+s2;
			t=0;
			k=-1;
		}
		k++;
	}
	if(t>0)
		{
			s2=pos[t]+s2;
		}
	cout<<s2<<endl;
	return 0;
}