#include <iostream>
using namespace std;

int binToDecimal(int binNum){
    int ans=0,pow=1;

    while(binNum>0){
        int rem=binNum % 10;
        ans+= rem*pow;

        binNum /=10;
        pow*=2;
    }

    return ans;//decimal form
}

int main() {
    cout << binToDecimal(101100) << endl;
    return 0;
}