public class Problem008
{
	public static int checkInt(String s)
	{
		int product = 1;
 
		for (int i = 0; i < 5; i++)
		{
			Character c = new Character(s.charAt(i));
			String tmp = c.toString();
			int temp = Integer.parseInt(tmp);
			product *= temp;
		}
		return product;
	}
 
	public static void main(String[] args)
	{
		long begin = System.currentTimeMillis();
		String BigNum = "7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450";
		String snip;
		int largest = 0;
 
		for (int i = 0; i <= (BigNum.length()-5); i++)
		{
			snip = "";
 
			for (int j = 0; j < 5; j++)
			{
				char c = BigNum.charAt(i+j);
				snip += c;
			}
 
			if (checkInt(snip) > largest)
				largest = checkInt(snip);
		}
		long end = System.currentTimeMillis();
		System.out.println(largest);
		System.out.println(end-begin + "ms");
	}
}

public class Problem007
{
	private static boolean isPrime(long n)
	{
		//returns 0 if not prime, 1 if prime
		if ((n % 2 == 0)&&(n != 2))
			return false;		// is even, therefore not prime
		for (long i = 3; i <= (n^(1/2)+1); i += 2)	// Skip all the even numbers
		{
			if (n % i == 0)
				return false;	//not prime
		}
		return true;
	}
 
	public static void main(String[] args)
	{
		long begin = System.currentTimeMillis();
		int NumPrimes = 1;
		long i = 2;
		while(NumPrimes <= 10001)
		{
			if (isPrime(i))
			{
				i++;
				NumPrimes++;
			}
			else i++;
		}
		long end = System.currentTimeMillis();
		System.out.println(i);
		System.out.println(end-begin + "ms");
	}	
}

public class Problem006
{
	private static long sum_squares(int n)
	{
		int total = 0;
		for (int i = 1; i <= n; i++)
			total += (i*i);
		System.out.println("sum_squares() = " + total);
		return total;
	}
 
	private static long squares_sum(int n)
	{
		long total = 0;
		for (int i = 1; i <= n; i++)
			total += i;
		total *= total;
		System.out.println("squares_sum() = " + total);
		return total;
	}
 
	public static void main(String args[])
	{
		long begin = System.currentTimeMillis();
		long omg_zombies = squares_sum(100) - sum_squares(100);
		long end = System.currentTimeMillis();
		System.out.println(omg_zombies);
		System.out.println(end-begin + "ms");
	}	
}

public class Problem005
{
	public static void main(String[] args)
	{
		long begin = System.currentTimeMillis();
		int i = 20;
		while (true)
		{
			if (	(i % 1 == 0) &&
				(i % 2 == 0) &&
				(i % 3 == 0) &&
				(i % 4 == 0) &&
				(i % 5 == 0) &&
				(i % 6 == 0) &&
				(i % 7 == 0) &&
				(i % 8 == 0) &&
				(i % 9 == 0) &&
				(i % 10 == 0) &&
				(i % 11 == 0) &&
				(i % 12 == 0) &&
				(i % 13 == 0) &&
				(i % 14 == 0) &&
				(i % 15 == 0) &&
				(i % 16 == 0) &&
				(i % 17 == 0) &&
				(i % 18 == 0) &&
				(i % 19 == 0) &&
				(i % 20 == 0) )
			{
				break;
			}
			i += 20;
		}
		long end = System.currentTimeMillis();
		System.out.println(i);
		System.out.println(end-begin + "ms");
	}	
}

public class Problem004
{
	private static int createPalindrome()
	{
		int total = 0;
		for (int i = 999; i >= 900; i--)
		{
			for (int j = 999; j >= 900; j--)
			{
				total = i * j;
				String s = Integer.toString(total);
				String s2 = new StringBuffer(s).reverse().toString();
				if (s.equals(s2))
					return total;
			}
		}
		return 0;
	}
 
	public static void main(String[] args)
	{
		long begin = System.currentTimeMillis();
		int answer = createPalindrome();
		long end = System.currentTimeMillis();
		System.out.println(answer);
		System.out.println(end-begin + "ms");
	}
}

public class Problem003b
{
	public static void main(String[] args)
	{
		long begin = System.currentTimeMillis();
		long n=600851475143L;
		for (long i = 2; i <= n; i++)
		{
			if (n % i==0)
			{
				System.out.println(i);
				n = n / i;
				i = 2;
			}
		}
		long end = System.currentTimeMillis();
		System.out.println(end-begin + "ms");
	}
}