Problem: JDELAY

/* package codechef;Problem: JDELAY Contest: LTIME64B  */

import java.util.*;
import java.lang.*;
import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
class Codechef
{
	public static void main (String[] args) throws java.lang.Exception
	{
		Scanner sc=new Scanner(System.in);
		int t=sc.nextInt();
		for (int i=0;i<t;i++)
		{
		    int count=0;
		    int n=sc.nextInt();
		    int s[]=new int[n];
		    int j[]=new int[n];
		    for (int k=0;k<n;k++)
		    {
		        s[k]=sc.nextInt();
		        j[k]=sc.nextInt();
		        int diff=j[k]-s[k];
		        if(diff>5)
		        count++;
		    }
		    System.out.println(count);
		}
	}
}