#include <iostream>
#include <cmath>
using namespace std;

void main() {

	int input = 0;
	int num = 0;
	int digit = 0;
	int decNum = 0;
	int max = 0;

	cout << "Number of Digits: ";
	cin >> max;
	
	cout << "Binary: ";
	cin >> input;

	double i = 0.0;

	while ( i < max ) {

		num = input / pow(10.0,i);
		digit = num % 10;

		if ( digit != 0 ) {

			decNum += pow(2.0,i);

		}
		i += 1.0;
	}

	cout << decNum << endl;

	main();
}