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:
from math import sqrt 

n = int(input())

def isPrime(num):
    if num==2 or num==3: return True
    #even number except 2 cannot be prime
    if num%2==0 or num<2: return False
    #only odd numbers
    for i in range(3, int(sqrt(num))+1, 2):
        if num%i==0:
            return False
    
    return True
    
  
if n%2!=0 and n>1:
    print(1)
else:
    m = 1
    while m<=1000:
        
        if not isPrime(n*m+1):
            print(m)
            break
        
        m+=1