/*
This is a Java Program to Implement Miller Rabin Primality Test Algorithm. Miller Rabin Primality Test is an algorithm which is used to determine if a given number is prime or not.
*/

/**
 ** Java Program to Implement Miller Rabin Primality Test Algorithm
 **/

import java.util.Scanner;
import java.util.Random;
import java.math.BigInteger;

/** Class MillerRabin **/
public class MillerRabin
{
    /** Function to check if prime or not **/
    public boolean isPrime(long n, int iteration)
    {
        /** base case **/
        if (n == 0 || n == 1)
            return false;
        /** base case - 2 is prime **/
        if (n == 2)
            return true;
        /** an even number other than 2 is composite **/
        if (n % 2 == 0)
            return false;
        long s = n - 1;
        while (s % 2 == 0)
            s /= 2;
        Random rand = new Random();
        for (int i = 0; i < iteration; i++)
            {
                long r = Math.abs(rand.nextLong());
                long a = r % (n - 1) + 1, temp = s;
                long mod = modPow(a, temp, n);
                while (temp != n - 1 && mod != 1 && mod != n - 1)
                    {
                        mod = mulMod(mod, mod, n);
                        temp *= 2;
                    }
                if (mod != n - 1 && temp % 2 == 0)
                    return false;
            }
        return true;
    }
    /** Function to calculate (a ^ b) % c **/
    public long modPow(long a, long b, long c)
    {
        long res = 1;
        for (int i = 0; i < b; i++)
            {
                res *= a;
                res %= c;
            }
        return res % c;
    }
    /** Function to calculate (a * b) % c **/
    public long mulMod(long a, long b, long mod)
    {
        return BigInteger.valueOf(a).multiply(BigInteger.valueOf(b)).mod(BigInteger.valueOf(mod)).longValue();
    }
    /** Main function **/
    public static void main (String[] args)
    {
        Scanner scan = new Scanner(System.in);
        System.out.println("Miller Rabin Primality Algorithm Test\n");
        /** Make an object of MillerRabin class **/
        MillerRabin mr = new MillerRabin();
        /** Accept number **/
        System.out.println("Enter number\n");
        long num = scan.nextLong();
        /** Accept number of iterations **/
        System.out.println("\nEnter number of iterations");
        int k = scan.nextInt();
        /** check if prime **/
        boolean prime = mr.isPrime(num, k);
        if (prime)
            System.out.println("\n"+ num +" is prime");
        else
            System.out.println("\n"+ num +" is composite");
    }
}

/*
Enter number

5510389

Enter number of iterations
2

5510389 is prime