#include
#include
#include
#include
using namespace std;
int main(){
int i,m,n=1,j;
long long int cout = 0;
string s1;
cin >> s1;
m = s1.length();
for (i = m-1; i >= 0; i--)
{
if (s1[i] > 'A') {
cout += (s1[i] - 55)*n;
}
else {
cout += (s1[i] - '0') * n;
}
n *= 16;
}
printf("%lld",cout);
}