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:
sieve=[*range(1000002)]
p=2
while p*p<1000001:
    if sieve[p]!=-1:
        for i in range(p+p,1000002,p):
            sieve[i]=-1
    p+=1
x=[]    
for i in range(2,1000002):
    if sieve[i]!=-1:
        x.append(i)
   
n=int(input()) 
m=1
k=0
while True:
    if (n*m+1) not in x:
        k=1
        break
    else:
        m+=1
if k==1:
    print(m)