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>
using namespace std;

#define fast_io ios_base::sync_with_stdio(false); cin.tie(NULL);
#define Fix( x ) setprecision( x ) << fixed
#define mem( a , x ) memset( a , x , sizeof( a ) )
#define bug( a , b ) cerr<< #a <<" = "<<a<<" , "<< #b <<" = "<<b<<"\n";
#define pb push_back
#define mp make_pair
#define ub upper_bound
#define lb lower_bound
#define FOR( i , a , b ) for( int i = a; i <= b; i++ )
#define ROF( i , a , b ) for( int i = a; i >= b; i-- )
#define sz( V ) (int)V.size( )
#define all( V ) V.begin( ),V.end( )
#define Found( S , val ) S.find( val ) != S.end( )
#define Unique( V ) sort( all( V ) ), V.erase( unique( all( V ) ), V.end() )
typedef pair < int , int > ii;
typedef pair < int , ii > iii;
typedef long long int LL;
typedef unsigned long long uLL;
const int inf = (int)1e9;
const LL INF = (LL)1e18;
const int N = 100005;
const int mod = 1000000007;
const double eps = 1e-8;
const double pi = acos( -1.0 );


int main( int argc, char const *argv[] ) {
        fast_io;
        string s;
        cin >> s;
        int n;
        cin >> n;
        while( sz(s)%n != 0 ) s += 'X';
        vector < string > V;
        string ans = "";
        for( int i = 0; i < s.size(); i += n ) {
                ans += s[i];
        }
        cout << ans << endl;
        return 0;
}