#include <bits/stdc++.h> using namespace std; string s; int main() { long long r=0,t=1,i; cin>>s; for( i=s.size()-1;i>=0;i--){ if(isdigit(s[i])){ r=r+(s[i]-'0')*t; }else{ r=r+(s[i]-'A'+10)*t; } t=t*16; } cout<<r; return 0; }