#include<iostream>
#include<math.h>
using namespace std;
int main()
{
	long long int a;
	cout<<"enter the no in binary\n";
	cin>>a;
	int b=0,j=0;
	int c;
	while(a!=0)
	{
		c=a%10;
		b=b+c*pow(2,j);
		j++;
		a=a/10;
	}
	cout<<b;
}
