Problem: PolandBall is a young, clever Ball. He is interested in prime numbers. He has stated a following hypothesis: "There exists such a positive integer n that for each positive integer m number n·m + 1 is a prime number".

Unfortunately, PolandBall is not experienced yet and doesn't know that his hypothesis is incorrect. Could you prove it wrong? Write a program that finds a counterexample for any n.

Input

The only number in the input is n (1 ≤ n ≤ 1000) — number from the PolandBall's hypothesis. 

Output

Output such m that n·m + 1 is not a prime number. Your answer will be considered correct if you output any suitable m such that 1 ≤ m ≤ 103. It is guaranteed the the answer exists.

Examples

Input

3


Output

1

Input

4


Output

2

Note

A prime number (or a prime) is a natural number greater than 1 that has no positive divisors other than 1 and itself.

For the first sample testcase, 3·1 + 1 = 4. We can output 1.

In the second sample testcase, 4·1 + 1 = 5. We cannot output 1 because 5 is prime. However, m = 2 is okay since 4·2 + 1 = 9, which is not a prime number.

Solution (in PYTHON):

Solution:

n = int(raw_input())

def primes(N):
	ps = []
	nums = range(N+1)
	for n in range(2, N+1):
		if nums[n] != 0:
			ps.append(n)
			for m in range(n*2, N+1, n):
				nums[m] = 0
	return ps

def solve(n):
	if n == 1:
		return 3
	if n % 2 == 1:
		return 1
	ps = primes(10**3)

	N = n+1
	for m in xrange(1,10**3+1):
		for p in ps:
			if p >= N: break
			if N % p == 0:
				# print N
				return m
		N += n

print solve(n)