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 primes(bound):
    sieve_size = (bound + 1) // 2
    sieve = [False] * sieve_size
    if bound < 2:
        return
    r = [2]
    for x in range(3, bound, 2):
        index = (x - 1) // 2
        if not sieve[index]:
            r.append(x)
            for i in range(index, sieve_size, x):
                sieve[i] = True
    return r

prime_set = set(primes(10**6+2))

if __name__ == '__main__':
    n = int(raw_input())

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