A. PolandBall and Hypothesis

time limit per test

2 seconds

memory limit per test

256 megabytes

input

standard input

output

standard output

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.

解题说明：水题，只要找到一个非素数即可。

#include<stdio.h>#include<string.h>int main(){ int n; scanf("%d",&n); if (n==1){printf("3\n"); }  else if (n==2){printf("4\n"); } else {printf("%d\n",n-2); } return 0;}