Zzuli:1068 binary number

Title Description

Put a binary number , Convert to the corresponding decimal number .

Input

Enter one that contains only ’0’ and ’1’ String , End with a carriage return , Represents a binary number . The binary number has unsigned bits , Length not exceeding 31.
 

Output

Output an integer , Is the decimal number corresponding to the binary number .

The sample input  Copy

100000000001

Sample output  Copy

2049

Tips

(1) Integer operations should be avoided pow And so on. double Type function , To avoid errors caused by truncation and rounding . (2) You can use the idea of recursion , Make full use of intermediate results . Similar ideas can refer to Qin Jiushao algorithm . Qin Jiushao algorithm is a polynomial simplification algorithm proposed by Qin Jiushao, a mathematician in Southern Song Dynasty . Calculate a polynomial f(x) = a0*xn + a1*x(n-1) + ... + an  It only needs n The multiplication and n Time in addition . The principle is a polynomial of degree f(x) It can be written in parentheses as follows ：f(x) =(( (a0*x + a1)*x + a2) * x + ... an-1) * x + an. Remove brackets from inside out to calculate , It only needs n The multiplication and n Time in addition .
This question outputs binary numbers from high to low , Corresponding polynomial coefficients a0, a1,....,an, and x The value of is 2. The recursive process is as follows ：
d = 0;
while( ch =  getchar(), ch != '\n')
     d  = d * 2 + (ch - '0');

#include <stdio.h>
int main()
{
	char ch;
	int d=0;
	while(scanf("%c",&ch),ch!='\n')
	{
		d=d*2+(ch-'0');
	}
	printf("%d",d);
	return 0;
}