Characters at multiples of X

A string S is passed as the input. A positive integer X is also passed as the input. The program must print the characters at positions which are multiples of X. 

Input Format: The first line contains S. The second line contains X. 

Output Format: The first line contains the characters at positions which are multiples of X. 

Boundary Conditions: Length of S will be from 3 to 100. 

Example Input/Output 1: 

Input: 

abcdexyzwqpoolj 

5 

Output: 

eqj 

Explanation: The multiples of 5 are like 5, 10, 15,... So the characters in these positions are e,q,j

Source Code:

#include<stdio.h>

#include <stdlib.h>

#include<string.h>

int main()

{

    char str[100];

    int x,i;

    fgets(str,100,stdin);

    scanf("%d",&x);

    for(i=1;i<=strlen(str);i++)

    {

       if(i%x==0)

        printf("%c",str[i-1]);

    }

}