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 PYTHON3):

Solution:
#THIS is a DUMB solution
"""

def isPrime(n):
    if n<=1:
        return False
    if n<=3:
        return True
    if n%2==0 or n%3==0:
        return False
    i=5
    while i**2<=n:
        if n%i==0 or n%(i+2)==0:
            return False
        i+=6
    return True

n=int(input())

i=1
while True:
    if not isPrime(n*i+1):
        break
    i+=1
print(i)
"""

"""
effective solution is 

given n*m+1 should not be prime

let us consider m = n+2
then   n*(n+2)+1 =>  n^2 + 2n + 1 =>  (n+1)^2
which cannot be a prime as it is divisible by n+1

BUT , m=n+2 will fail at edges cases becoz at n=1000 m will be 1002
which is not accepted
so let us again consider m=n-2 => (n-1)^2

Input
n (1 ≤ n ≤ 1000)
Output
Output such m that n·m + 1 is not a prime number. 
any suitable m such that 1 ≤ m ≤ 1000.
 It is guaranteed the the answer exists.

"""
n=int(input())
print(n+2 if n<908 else n-2)