Twin Prime Pairs In a Given Range in Java

Write a program in Java to generate all the twin primes in the range 1 to N, where the value of N is entered by the user.

A twin prime is a pair of prime numbers with a difference of 2.

For example: 3, 5.

Sample Input:
N = 50
Sample Output:
3, 5
5, 7
11, 13
17, 19
29, 31
41, 43

import java.io.*;
class TwinPrime{
    public static void main(String args[])throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        System.out.print("N = ");
        int n = Integer.parseInt(br.readLine());
        for(int i = 1; i <= n - 2; i++){
            if(isPrime(i) && isPrime(i + 2))
                System.out.println(i + ", " + (i + 2));
        }
    }
    public static boolean isPrime(int num){
        int f = 0;
        for(int i = 1; i <= num; i++){
            if(num % i == 0)
                f++;
        }
        return f == 2;
    }
}