#include <bits/stdc++.h>
using namespace std;

int main()
{
	int N;
	cin >> N;

	auto IsPrime = []( int num ) -> bool
	{
		if (num < 2) return false;
		else if (num == 2) return true;
		else if (num % 2 == 0) return false;
		for ( int i = 3; i * i <= num; i += 2 ) {
			if (num % i == 0) return false;
		}
		return true;
	};

	int ans;
	for( int n = N - 100; n <= N + 100; n++ ) {
		if( n == 1 || IsPrime( n ) ) continue;
		ans = n;
		break;
	}

	cout << ans << endl;
}