#include <bits/stdc++.h>
using namespace std;
int isp(int d) {
  for (int i = 3; i < d / 2; ++i)
    if (d % i == 0) return 0;
  return 1;
}
int main() {
  int n, k = 1, t = 0, l;
  cin >> n;
  if (n % 2 != 0 && n != 1)
    cout << k;
  else {
    while (1) {
      if (k * n + 1 == 2) {
        cout << 3;
        break;
      } else if (isp(k * n + 1) == 0) {
        cout << k;
        break;
      } else {
        ++k;
      }
    }
  }
}

### Prompt

Generate a cpp solution to the following 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.

### Response

```cpp
#include <bits/stdc++.h>
using namespace std;
int isp(int d) {
  for (int i = 3; i < d / 2; ++i)
    if (d % i == 0) return 0;
  return 1;
}
int main() {
  int n, k = 1, t = 0, l;
  cin >> n;
  if (n % 2 != 0 && n != 1)
    cout << k;
  else {
    while (1) {
      if (k * n + 1 == 2) {
        cout << 3;
        break;
      } else if (isp(k * n + 1) == 0) {
        cout << k;
        break;
      } else {
        ++k;
      }
    }
  }
}

```