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:
def IsPrime(n):
    if n == 2 or n == 3:
        return True
    if n == 1:
        return False
    for i in range(2,int(n**0.5)+1):
        if n%i == 0:
            return False
    if i == int(n**0.5) and n%i != 0:
        return True
    else:
        return False


def Hypothesis():
    n = int(raw_input())
    if n%2 != 0 and n != 1:
        print 1
    else:
        for i in range(1,1001):
            if not IsPrime((n*i)+1):
                print i
                break
            
Hypothesis()