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;
bool SortbySecDesc(const pair<long long, long long> &a,
                   const pair<long long, long long> &b) {
  return a.second > b.second;
}
bool sortinrev(const pair<int, int> &a, const pair<int, int> &b) {
  return (a.first > b.first);
}
long long Prime[3000000], nPrime;
long long mark[10000002];
void seive(long long int n) {
  long long int i, j, limit = sqrt(n * 1.0) + 2;
  mark[1] = 1;
  for (i = 4; i <= n; i += 2) mark[i] = 1;
  Prime[nPrime++] = 2;
  for (i = 3; i <= n; i += 2) {
    if (!mark[i]) {
      Prime[nPrime++] = i;
      if (i <= limit) {
        for (j = i * i; j <= n; j += i * 2) {
          mark[j] = 1;
        }
      }
    }
  }
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(nullptr);
  ;
  long long n;
  cin >> n;
  seive(10000);
  for (int i = 1; i <= 1000; i++) {
    long long ans = n * i + 1;
    if (mark[ans] == 1) {
      cout << i << "\n";
      ;
      return 0;
    }
  }
  return 0;
}