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:
def eratosthenes(n):
    sieve = list(range(n + 1))
    #print(sieve)
    sieve[1] = 0
    prime = []
    for i in sieve:
        if i > 0:
            prime.append(i)
            for j in range(i * i, len(sieve), i):
                sieve[j] = 0
    return prime


n = int(input())
ans = 0
if n == 1:
    ans = 3
elif n % 2:
    ans = 1
else:
    p = eratosthenes(n * 1000)
    for i in range(1, 1001):
        if i * n + 1 not in p:
            ans = i
            break

print(ans)