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:
import sys
import math

#to read string
get_string = lambda: sys.stdin.readline().strip()
#to read list of integers
get_int_list = lambda: list( map(int,sys.stdin.readline().strip().split()) )
#to read non spaced string and elements are integers to list of int
get_intList_from_str = lambda: list(map(int,list(sys.stdin.readline().strip())))
#to read non spaced string and elements are character to list of character
get_charList_from_str = lambda: list(sys.stdin.readline().strip())
#get word sepetared list of character
get_char_list = lambda: sys.stdin.readline().strip().split() 
#to read integers
get_int = lambda: int(sys.stdin.readline())
#to print faster
pt = lambda x: sys.stdout.write(str(x))

#--------------------------------WhiteHat010--------------------------------#
def isprime(n):
    i = 2
    while i*i <= n:
        if n%i == 0:
            return False
        i += 1
    return True

n = get_int()
i = 1
while True:
    if not isprime(n*(i)+1):
        print(i)
        break
    i += 1