Problem:
Score : 200 points

Problem Statement

You are given a string S consisting of lowercase English letters.
We will write down this string, starting a new line after every w letters. Print the string obtained by concatenating the letters at the beginnings of these lines from top to bottom.

Constraints

1 \leq w \leq |S| \leq 1000

S consists of lowercase English letters.

w is an integer.

Input

Input is given from Standard Input in the following format:

S
w

Output

Print the desired string in one line.

Sample Input 1

abcdefgh
3

Sample Output 1

adg

When we write down abcdefgh, starting a new line after every three letters, we get the following:

abc

def

gh

Concatenating the letters at the beginnings of these lines, we obtain adg.

Sample Input 2

lllll
1

Sample Output 2

lllll

Sample Input 3

souuundhound
2

Sample Output 3

suudon

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

program aaa
implicit none
integer :: i,j,k,n,a,b,len,w

character(len=1000) :: s
character(len=1000) :: s2

read(*,*) s
read(*,*) w

s2=""
a=1

do while(a <= len_trim(s))
s2 = s2(1:len_trim(s2))//s(a:a)

a = a + w
enddo

write(*,*) s2(1:len_trim(s2))

end program