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 CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
const long long maxn = (long long)5e5;
const long long linf = (long long)1e16;
const long long mod = (long long)1e9 + 7;
long long n;
long long f(long long x) {
  for (long long i = 2; i * i <= x; i++) {
    if (x % i == 0) {
      return 1;
    }
  }
  return 0;
}
int main() {
  cin >> n;
  if (n == 1) {
    cout << 3;
    return 0;
  }
  if (n % 2 == 1 && n > 1) {
    cout << 1;
    return 0;
  }
  for (long long i = 2; i <= maxn; i++) {
    if (f(n * i + 1)) {
      cout << i;
      return 0;
    }
  }
  return 0;
}