import java.util.Scanner;

class Main{
	static boolean isprime(long x){
		if(x==1) return false;
		for(long i=2;i*i<=x;i++) if(x%i==0) return false;
		return true;
	}
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		while(sc.hasNext()){
			long n=sc.nextLong();
			if(isprime(n) || n==4) System.out.println(n);
			else{
				boolean flag=true;
				for(long i=3;i*i<=n;i++){
					if(n%i==0){
						System.out.println(i);
						flag=false;
						break;
					}
				}
				if(flag) System.out.println(n/2);
			}
		}
	}
}