#include<bits/stdc++.h> using namespace std; int main(){ int n; string s; cin>>s; while(s.size()%4!=0){ s='0'+s; } int l=s.size(); for(int i=0; i<l-3; i=i+4){ n=(s[i]-'0')*8+(s[i+1]-'0')*4+(s[i+2]-'0')*2+(s[i+3]-'0')*1; if(n>=10){ cout<<char(n-10+'A'); }else{ cout<<n; } } return 0; }