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;
/*------- Constants---- */

#define LL                      long long
#define Ulong                   unsigned long long
#define REP(i,n)                for(long long i=0; i < n ; i++ )
#define mp                      make_pair
#define pb                      push_back
#define all(x)                  (x).begin(),(x).end()
#define PI                      acos(-1.0)
#define EPS                     1e-14
#define F                       first
#define S                       second
#define di(x)                   int x; input(x)
#define in(x)                   input(x)
#define in2(x,y)                in(x),in(y)
#define in3(x,y,z)              in(x),in2(y,z)
#define lc                      ((n)<<1)
#define rc                      ((n)<<1|1)
#define db(x)                   cout << #x << " -> " << x << endl
#define nl                      cout<<endl
#define ms(ara_name,value)      memset(ara_name,value,sizeof(ara_name))
#define IO                      ios_base::sync_with_stdio(0);cin.tie(0)
#define READ                    freopen("/home/matrixcode/Desktop/in.txt","r",stdin)
#define WRITE                   freopen("out.txt","w",stdout)
template<class T> inline void input(T &x) {
    char c = getchar();x = 0;
    int neg = 0;
    for(; ((c<48 || c>57) && c != '-'); c = getchar());
    if(c=='-'){neg = 1;c = getchar();}
    for(; c>47 && c<58 ; c = getchar()){x = (x<<1) + (x<<3) + c - 48;}
    if(neg) x = -x;
}
inline long long bigmod(long long p,long long e,long long M){
    long long ret = 1;
    for(; e > 0; e >>= 1){
        if(e & 1) ret = (ret * p) % M;
        p = (p * p) % M;
    } return ret;
}
template <class T> inline T gcd(T a,T b){if(b==0)return a;return gcd(b,a%b);}
template <class T> inline T modinverse(T a,T M){return bigmod(a,M-2,M);}

/***************************** END OF TEMPLATE *******************************/


const int N = 1001;

int main()
{
    string s;
    int n;
    cin >> s >> n;
    for(int i = 0; i < s.size(); i += n) {
        cout << s[i];
    }
}