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
import bisect
import itertools
import random

def pow_mod(a, n, m):
    if n == 0:
        return 1
    if n == 1:
        return a % m
    ans = pow_mod(a, n // 2, m)
    ans = ans * ans % m
    if n % 2 == 1:
        ans = ans * a % m
    return ans

def MillerRabin_PrimalityTesting(n):
    if n == 2 or n == 3:
        return True
    if n % 2 == 0:
        return False
    if n % 3 == 0:
        return False
    R = 0
    D = n - 1
    while D % 2 == 0:
        R += 1
        D //= 2
    #print([n, R, D])
    for _ in range(random.randint(10, 15)):
        A = random.randint(2, n - 1)
        X = pow_mod(A, D, n)
        #X = A ** D % n
        if X == 1 or X == n - 1:
            continue
        flag = 0
        for i in range(1, R):
            X = pow_mod(X, 2, n)
            #X = X ** 2 % n
            if X == 1:
                return False
            if X == n - 1:
                flag = 1
                break
        if flag == 1:
            continue
        return False
    return True

def main():
    n = int(input())
    for i in range(1, 1001):
        val = n * i + 1
        if MillerRabin_PrimalityTesting(val) == False:
            print(i)
            break

if __name__ == "__main__":
    main()