#include<bits/stdc++.h> using namespace std; string s; long long n,m=0; int main(){ cin>>s; for(int i=0;i<=s.size();i++){ if(s[i]>='A'&&s[i]<='F'){ n=s[i]-'A'+10; }else{ n=s[i]-'0'; } m=m*16+n; } cout<<m; return 0; }