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 <bits/stdc++.h>

#define REP(i,n) for(int i = 0; i < (n); ++i)
#define REP1(i,n) for(int i = 1; i <= (n); ++i)
#define RREP(i, n) for(int i = (n) - 1; i >= 0; --i)
#define ALL(a) begin(a), end(a)
#define CEIL(a,b) ((a) / (b) + ((a) % (b) == 0 ? 0 : 1))
#define X first
#define Y second

using namespace std;
using ll = long long;
using vi = vector<int>;
using pii = pair<int, int>;

constexpr int MOD = 1e9 + 7;
constexpr int INF = 1e9 + 1;
constexpr ll LLINF = 4 * 1e18 + 1;
// constexpr int INF = 2147483647; // 2 * 1e9
// constexpr ll LLINF = 9223372036854775807; // 9 * 1e18

const int dx[] = {1, 0, -1, 0, 1, -1, -1, 1, 0};
const int dy[] = {0, 1, 0, -1, 1, 1, -1, -1, 0};

int main(){
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	string  s;
	int w;
	cin >> s >> w;
	for(int i = 0; i < s.size(); i += w) cout << s[i];
	cout << "\n";
	return 0;
}