#include <iostream>
#include <cmath>
using namespace std;
int main() {
    int b = 0,c = 0,n = 0;
    int sum = 0;
    cin >> n;
    while(n != 0) {
        b = n % 10;
        sum += b * pow(2,c);
        n = n /10;
        c+= 1;
    }
    cout << sum << " ";
	return 0;
}