Problem:
Score : 100 points

Problem Statement

Snuke has a grid consisting of three squares numbered 1, 2 and 3.
In each square, either 0 or 1 is written. The number written in Square i is s_i.

Snuke will place a marble on each square that says 1.
Find the number of squares on which Snuke will place a marble.

Constraints

Each of s_1, s_2 and s_3 is either 1 or 0.

Input

Input is given from Standard Input in the following format:

s_{1}s_{2}s_{3}

Output

Print the answer.

Sample Input 1

101

Sample Output 1

2

A marble will be placed on Square 1 and 3.

Sample Input 2

000

Sample Output 2

0

No marble will be placed on any square.

Solution in Fortran (gfortran v4.8.4) (judge verdict: Accepted)

module ABC081

	! <module>s to import
	use, intrinsic :: iso_fortran_env


	! require all variables to be explicitly declared
	implicit none


	! accessibility of <subroutine>s and <function>s in this <module>
	public  :: ABC081_A


	! constants for this <module>
	integer( kind=INT32 ), parameter, private :: num_char = 3


	! contained <subroutine>s and <function>s are below
	contains


	subroutine ABC081_A

		! variables for this <subroutine>
		character(len=num_char, kind=1) :: buffer
		integer( kind=INT16 )           :: itr, count

		! STEP.01
		! read out the target positive integers
		read *, buffer

		! STEP.02
		! count the number of the `1`
		count = 0

		do itr = 1, num_char, 1
			if( ichar( buffer(itr:itr) ) .eq. ichar('1') ) count = count+1
		end do

		! STEP.03
		! output the result
		write( unit=OUTPUT_UNIT, fmt='(I0)', advance='yes' ) count

		! STEP.END
		return

	end subroutine ABC081_A

end module ABC081


program main

	! <module>s to import
	use, non_intrinsic :: ABC081

	! require all variables to be explicitly declared
	implicit none

	call ABC081_A


end program main