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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <cctype>
#include <cmath>
#include <functional>
#include <map>
#include <cstdio>
#include <stack>
using namespace std;
typedef long long ll;

#define reps(i, s, n) for (int(i) = (s); (i) < (n); (i)++)
#define rep(i, n) reps(i, 0, n)

int main(){
    int w;
    string str;
    string ans = "";
    cin >> str;
    cin >> w;
int cnt=0;
if(str.length()%w != 0){
    rep(i, str.length()/w+1){
        cnt++;
        
            ans += str[i*w];
        
    }
}else{
    rep(i, str.length()/w){
        cnt++;
        
            ans += str[i*w];
        
    }
}
    cout << ans << endl;

    return 0;
}