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 prime(n):
    if n==0 or n==1:
        return 0
    if n%2==0:
        return 0
    else:
        flag=1
        for i in xrange(3,int(n**0.5)+2):
            if n%i==0:
                flag=0
                break
        if flag==1:
            return 1
        else:
            return 0
            
n = int(raw_input())
if n==1:
    print "3"
elif n==2:
    print "7"
elif n%2==0:
    for i in xrange(1,1001):
        if prime(n*i+1)==0:
            print i
            break
    #print 1 if not prime(n+1) else 2
else:
    print "1"