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

def sieve(limit=1000000):
    yield 2
    sub_limit = int(limit**0.5) 
    flags = [False, False] + [True] * (limit - 2)   
#     flags = BitString(limit)
    # Step through all the odd numbers
    for i in range(3, limit, 2):       
        if flags[i] is False:
#        if flags[i] is True:
            continue
        yield i
        # Exclude further multiples of the current prime number
        if i <= sub_limit:
            for j in range(i*3, limit, i<<1):
                flags[j] = False

n = int(input())
primes = sieve(9999)
x = 1
while n == n:
    if (n*x+1) in primes:
        x+=1
    else:
        break
print(x)