Problem link-https://www.codechef.com/TSCO2017/problems/TSECJ106
solution-
import java.util.Arrays;
import java.util.Scanner;
public class rods
{
public static void main(String[] args)
{
Scanner sc=new Scanner(System.in);
int n=sc.nextInt();
int a[]=new int[n];
for(int i=0;i<n;i++)
{
a[i]=sc.nextInt();
}
int cnt=1;
int maintain=0;
Arrays.sort(a);
for(int i=0;i<n;i++)
{
if(i==0)
maintain=(a[i]+6);
else
{
if(a[i]>maintain)
{
maintain=a[i]+6;
cnt++;
}
}
}
System.out.println(cnt);
}
}