aa

test

import java.util.Scanner;
public class Try {
    public static void main(String[] args) {
        Scanner in=new Scanner(System.in);
        int n=in.nextInt();
        Scanner S=new Scanner(System.in);
        String []s=new String[30];
       for (int i = 0; i < n; i++) {
        s[i]=S.nextLine();       
       }
       String []tm=new String [2];
       String []tm2=new String [2];
       int c=0;
       for(int i=0;i<n;i++)
       {
           tm=s[i].split(" ");
           for(int j=0;j<i;j++)
           {
               tm2=s[j].split(" ");
               if( tm[0].matches(tm2[1]))
                   c++;
               if(tm[1].matches(tm2[0]))
                   c++;
               
           }
       }
       System.out.print(c);
       
    }
    
}

4
100 42
42 100
5 42
100 5

package utitity.mahmoud.junittutorial;

import java.util.Scanner;

public class Test {

    public static void main(String[] args) {
        Scanner S = new Scanner(System.in);
        int n=Integer.parseInt(S.nextLine());
        String []s=new String[30];
        for (int i = 0; i < n; i++) {
            s[i]=S.nextLine();
        }
        String []tm=new String [2];
        String []tm2=new String [2];
        int c=0;
        for(int i=0;i<n;i++)
        {
            tm=s[i].split(" ");
            for(int j=0;j<i;j++)
            {
                tm2=s[j].split(" ");
                if( tm[0].matches(tm2[1]))
                    c++;
                if(tm[1].matches(tm2[0]))
                    c++;

            }
        }
        System.out.print(c);
    }
}