#include<bits/stdc++.h>
using namespace std;
int main()  
{
    string s;
    cin>>s;
    int r=0;
    long long  k=1;
    for(int i=s.size()-1;i>=0;i--)
    {
    	if(s[i]>='A' && s[i]<='F')
    	{
    		r=r+(s[i]-55)*k;
    		k=k*16;
		}
		else
		{
			r=r+(s[i]-48)*k;
    	    k=k*16;
		}
	}
	cout<<r;
	return 0;
}
/**************************************************************
	Problem: 1292
	User: chenkexin
	Language: C++
	Result: Wrong Answer
****************************************************************/