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 C (GCC 5.4.1) (judge verdict: Accepted)

#include<stdio.h>
#include<math.h>
#include<stdlib.h>
#define rep(index,num) for(int index=0;index<num;index++)
#define scan(argument) scanf("%d",&argument)
#define prin(argument) printf("%d\n",argument)
#define eps 1e-15
typedef long long ll;
int main(){
	char str[1001];
	int w;
	scanf("%s",str);
	scan(w);
	rep(i,1000){
		if(str[i]=='\0'){
			break;
		}
		else if(i%w==0){
			printf("%c",str[i]);
		}
	}
	printf("\n");
	return 0;
}