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;
int MOD(int a, int b) {
  if (a > b)
    return a - b;
  else
    return b - a;
}
long long int max3(long long int a, long long int b, long long int c) {
  return max(c, max(a, b));
}
long long int power(long long int x, long long int y, long long int p) {
  long long int res = 1;
  x = x % p;
  while (y > 0) {
    if (y & 1) res = (res * x) % p;
    y = y >> 1;
    x = (x * x) % p;
  }
  return res;
}
long long int max(long long int a, long long int b) { return (a > b) ? a : b; }
long long int min(long long int a, long long int b) { return (a < b) ? a : b; }
long long int gcd(long long int a, long long int b) {
  if (b == 1)
    return 1;
  else if (a % b == 0)
    return b;
  else
    return gcd(b, a % b);
}
bool prime[100005];
bool vis[100005];
void prim() {
  memset(prime, 0, sizeof(prime));
  memset(vis, 0, sizeof(vis));
  int i, j, k;
  prime[1] = false;
  vis[1] = true;
  for (i = 1; i < 100005; i++) {
    if (!vis[i]) {
      prime[i] = true;
      for (j = i; j < 100005; j += i) {
        vis[j] = true;
      }
    }
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  prim();
  int n, i;
  cin >> n;
  for (i = 1; i < 1001; i++) {
    if (!prime[n * i + 1]) {
      cout << i << "\n";
      return 0;
    }
  }
  return 0;
}