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:

'''
Light temp.
'''
import sys
from math import ceil,floor,log2,sqrt

def readall():
    return [int(x) for x in sys.stdin.read().split()]

def u():
    return [int(i) for i in sys.stdin.readline().split()]


n = u()[0]

def pc(x):
    if x == 2:
        return True
    
    if x % 2 == 0:
        return False
    
    i = 3
    while i**2 <= x:
        if x % i == 0:
            return False
        i += 2
    return True

for i in range(1,1001):
    if not pc(n*i+1):
        print(i)
        exit()

#if num is odd and greater than special case 1 - then take whatever odd number to generat a + 1 div by 2
#if n is even tho, take a number m s.t. n*m % 3 == 2