#include<bits/stdc++.h> using namespace std; int n,a,sum=0; int main(){ string s; cin>>s; if(s=="0"){cout<<0; return 0;} int a; string h,x=""; for(int i=0;i<s.size();i++){ h=""; if(s[i]<='9'){ a=s[i]-'0'; }else{ a=s[i]-'A'+10; } for(int j=1;j<=4;j++){ h=char(a%2+'0')+h; a=a/2; }x+=h; } while(x[0]=='0'){ x.erase(0,1);} long long t=1,r,i; for(i=x.size()-1;i>=0;i--){ r=r+(x[i]-'0')*t; t=t*2; } cout<<r; return 0; }