PolandBall and Hypothesis

题意翻译

对于一个数n(1≤n≤1000)，输出一个m，使得n·m+1不是质数且1≤m≤1000。

题目描述

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 $ .

输入输出格式

输入格式

The only number in the input is $ n $ ( $ 1<=n<=1000 $ ) — number from the PolandBall's hypothesis.

输出格式

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<=10^{3} $ . It is guaranteed the the answer exists.

输入输出样例

输入样例 #1

3

输出样例 #1

1

输入样例 #2

4

输出样例 #2

2

说明

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.